2024-03-28T13:22:13Zhttp://oai.recercat.cat/request
oai:recercat.cat:2072/2213092013-12-17T11:45:23Zhdl_2072_220002
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorBarbosa Torralbo, José
authorFiguera Gazo, Pilar
authorDorio Alcaraz, Inmaculada
authorFonrodona Baldajos, Gemma
authorGonzález Azón, María del Carmen
authorPrades Nebot, Anna
authorTorrado Fonseca, Mercè
2013-11-13T08:53:12Z
2013-11-13T08:53:12Z
2003-02
2013-12-17T11:45:23Z
2013-12-17T11:45:23Z
2013-12-17T11:45:23Z
http://hdl.handle.net/2445/47746
Abans de presentar l’estudi d’inserció professional dels químics i els seus resultats, creiem oportú fer referència als antecedents interns i externs al nostre context institucional i que, sens dubte, expliquen la presència avui d’aquest informe. La Universitat de Barcelona des de fa més d’una dècada, i a càrrec del Gabinet d’Avaluació i Innovació Universitària (actualment UAPI), realitza periòdicament estudis en profunditat que han estat la base per a la reflexió i millora dels diferents ensenyaments. En el cas concret dels estudis sobre la inserció laboral dels seus graduats i graduades, aquesta institució n’ha estat pionera a nivell nacional i disposa en aquests moments d’una de les bases de dades més complerta de Catalunya...
108 p.
application/pdf
cat
TRALS. Universitat de Barcelona
Reproducció del document original
cc-by-nc (c) Grup de Recerca TRALS. Universitat de Barcelona, 2003
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by-nc/3.0/es/">http://creativecommons.org/licenses/by-nc/3.0/es/</a>
Químics
Desenvolupament professional
Chemists
Career development
Els Químics de la UB. Estudi d’inserció professional. Primera part
info:eu-repo/semantics/report
oai:recercat.cat:2072/2229632014-01-30T23:20:14Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorMorales-Gutiérrez, F. J.
authorHermo Outeiral, Ma. del Pilar
authorBarbosa Torralbo, José
authorBarrón Bueno, Dolores
2014-01-30T09:53:00Z
2014-01-30T09:53:00Z
2014-00-00
2014-01-30T09:53:00Z
2014-01-30T23:20:14Z
2014-01-30T23:20:14Z
2014-01-30T23:20:14Z
0731-7085
http://dx.doi.org/doi:10.1016/j.jpba.2014.01.014
http://hdl.handle.net/2445/49272
The aim of this work was the identification of new metabolites and transformation products (TPs) in chicken muscle from Enrofloxacin (ENR), Ciprofloxacin (CIP), Difloxacin (DIF) and Sarafloxacin (SAR), which are antibiotics that belong to the fluoroquinolones family. The stability of ENR, CIP, DIF and SAR standard solutions versus pH degradation process (from pH 1.5 to 8.0, simulating the pH since the drug is administered until its excretion) and freeze-thawing (F/T) cycles was tested. In addition, chicken muscle samples from medicated animals with ENR were analyzed in order to identify new metabolites and TPs. The identification of the different metabolites and TPs was accomplished by comparison of mass spectral data from samples and blanks, using liquid chromatography coupled to quadrupole time-of-flight (LC-QqToF) and Multiple Mass Defect Filter (MMDF) technique as a pre-filter to remove most of the background noise and endogenous components. Confirmation and structure elucidation was performed by liquid chromatography coupled to linear ion trap quadrupole Orbitrap (LC-LTQ-Orbitrap), due to its mass accuracy and MS/MS capacity for elemental composition determination. As a result, 21 TPs from ENR, 6 TPs from CIP, 14 TPs from DIF and 12 TPs from SAR were identified due to the pH shock and F/T cycles. On the other hand, 14 metabolites were identified from the medicated chicken muscle samples. Formation of CIP and SAR, from ENR and DIF, respectively, and the formation of desethylene-quinolone were the most remarkable identified compounds.
33 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/doi:10.1016/j.jpba.2014.01.014
Journal of Pharmaceutical and Biomedical Analysis, 2013
(c) Elsevier B.V., 2013
info:eu-repo/semantics/openAccess
Quinolones
Metabòlits
Gallines
Músculs
Antibiòtics
Avaluació del risc per la salut
Espectrometria de masses
Quinolone antibacterial agents
Metabolites
Hens
Muscles
Antibiotics
Health risk assessment
Mass spectrometry
High-Resolution Mass Spectrometry applied to the identification of new metabolites and transformation products of quinolones in chicken muscle tissues
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2128612014-09-17T22:32:08Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorBarbosa Torralbo, José
authorBarrón Bueno, Dolores
authorHermo Outeiral, Ma. del Pilar
authorNavalón, Alberto
authorBallesteros, Óscar
2009
1223-7221
http://hdl.handle.net/2445/44487
In this work methods for the multiresidue determination of the series of quinolones include in the European regulation in food of animal origin are de veloped and validated in line with Commission Decision 2002/657/EC in terms of linearity, decision limit, capability detection, precision and stability. Mult iresidue methods were established to allow the determination of quinolones covered by EU legislation in 2377/90/EC in muscle of chicken, turkey, pig and cow, plasma of cow and pig, liver of pig and milk of cow. First an extraction step was optimized and a SPE step was applied to clean!up and preconcentrate quinolones prior to their separation by CE or LC and determination by CE!UV, LC!UV, LC!Fl, LC!MS with different ion sources (ESI ,ApCI) and different mass analyser (Q, ToF) and LC!E SI!QqQ tandem mass spectrometry. The limits of quantification obtained are always lower than Maxim um Residue Limit (MRL) established by EU for quinolones in animal products and they can be applied to the control of quinolones in foodstuffs of animal origin . Finally the proposed methods were applied to determine quinolones in samples of turkey and pig muscle, pig plasma and milk of cow. Excellent quality parameters and reduced time of analysis were obtained when LC!ESI!MS/MS is used, although the others techniques presented too satisfactory results.
15 p.
application/pdf
eng
Universitatea Ovidius
Ovidius University Annals of Chemistry, 2009, vol. 20, num. 2, p. 165-179
(c) Universitatea Ovidius, 2009
info:eu-repo/semantics/openAccess
Quinolones
Teixits (Histologia)
Quinolone antibacterial agents
Tissues
Determination and characterization of quinolones in foodstuffs of animal origin by CE-UV, LC-UV, LC-Fl, LC-MS and LC-MS/MS
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2243412015-01-08T23:51:45Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorJunza Martínez, Alexandra
authorBarbosa, S.
authorCodony Salcedo, Rafael
authorJuvert, A.
authorBarbosa Torralbo, José
authorBarrón Bueno, Dolores
2014-00-00
0021-8561
http://dx.doi.org/10.1021/jf405554z
http://hdl.handle.net/2445/50576
The presence of residues of antibiotics, metabolites, and thermal transformation products (TPs), produced during thermal treatment to eliminate pathogenic microorganisms in milk, could represent a risk for people. Cow"s milk samples spiked with enrofloxacin (ENR), ciprofloxacin (CIP), difloxacin (DIF), and sarafloxacin (SAR) and milk samples from cows medicated with ENR were submitted to several thermal treatments. The milk samples were analyzed by liquid chromatography-mass spectrometry (LC-MS) to find and identify TPs and metabolites. In this work, 27 TPs of 4 quinolones and 24 metabolites of ENR were found. Some of these compounds had been reported previously, but others were characterized for the first time, including lactose-conjugated CIP, the formamidation reaction for CIP and SAR, and hydroxylation or ketone formation to produce three different isomers for all quinolones studied.
46 p.
application/pdf
eng
American Chemical Society, Books and Journals Division]
Versió postprint del document publicat a: http://dx.doi.org/10.1021/jf405554z
Journal of Agricultural and Food Chemistry, 2013
(c) American Chemical Society, Books and Journals Division], 2013
info:eu-repo/semantics/openAccess
Antibiòtics
Llet
Quinolones
Metabòlits
Cromatografia de líquids
Espectrometria de masses
Estructura química
Antibiotics
Milk
Quinolone antibacterial agents
Metabolites
Liquid chromatography
Mass spectrometry
Chemical structure
Identification of metabolites and thermal transformation products of quinolones in raw cow milk by liquid chromatography coupled to high resolution mass spectrometry
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2622712016-05-31T22:44:15Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorPérez-Maciá, María Ángeles
authorBringue Tomás, Roger
authorIborra Urios, Montserrat
authorTejero Salvador, Xavier
authorCunill García, Fidel
2016-05-31T07:29:06Z
2015-06-11
2016-05-31T07:29:11Z
info:eu-repo/date/embargoEnd/2017-06-11
0263-8762
http://dx.doi.org/10.1016/j.cherd.2015.06.007
654737
http://hdl.handle.net/2445/99061
The thermodynamic equilibrium of the bimolecular dehydration of 1-butanol to di-n-butyl ether (DNBE) and water in the liquid phase was studied. Equilibrium experiments were performed at 4 MPa and in the temperature range of 413-463 K over the ion exchange resin Amberlyst-70. The thermodynamic equilibrium for the side reactions (dehydration to 1-butene, olefins isomerization, olefins hydration and branched ether formation) was also studied. The equilibrium constant for the dehydration reaction of 1-butanol to di-n-butyl ether and water was found to be independent on the operating temperature, within the limits of the experimental error ( 5.2%). The experimental equilibrium constants at 413-463 K allows to estimate the standard enthalpy change of reaction (ΔrH0(l) = -0.3 ± 2.9 kJ¿mol-1) and the standard entropy change of reaction (ΔrS0(l) = 26.8 ± 6.7 J¿mol-1¿K-1). From these values the standard formation enthalpy (ΔfH0DNBE,(l)) and the molar entropy of DNBE (S0DNBE,(l)) at 298.15 K were computed to be -370.5 ± 10.9 kJ¿mol-1 and 408.3 ± 6.8 J¿mol-1¿K-1 respectively
10 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.cherd.2015.06.007
Chemical Engineering Research & Design, 2015, vol. 102, p. 186-195
cc-by-nc-nd (c) Elsevier B.V., 2015
info:eu-repo/semantics/embargoedAccess
<a href="http://creativecommons.org/licenses/by-nc-nd/3.0/es">http://creativecommons.org/licenses/by-nc-nd/3.0/es</a>
Èters
Alcohol butílic
Resines de bescanvi iònic
Ethers
Butanol
Ion exchange resins
Thermodynamic equilibrium for the dehydration of 1-butanol to di-n-butyl ether
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2665062016-07-27T22:37:08Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorSubirats i Vila, Xavier
authorRosés Pascual, Martí
authorBosch, Elisabeth
2016-07-27T10:33:52Z
2016-07-27T10:33:52Z
2009
2016-07-27T10:33:57Z
1132-1369
574681
http://hdl.handle.net/2445/101329
Es bien sabido que el pH de la fase móvil es una variable fundamental en la separación de sustancias ionizables en cromatografía de líquidos, ya que de él depende el grado de ionización de los analitos presentes en la mezcla problema. En el desarrollo de métodos analíticos se requiere pues, ejercer un control eficiente sobre el pH mediante la elección de un tampón adecuado. En cromatografía de líquidos en fase inversa, suelen usarse solucio- nes hidro-orgánicas tamponadas como fases móviles. Habitualmente éstas suelen prepararse añadiendo el volumen adecuado de un disolvente orgánico, típicamente acetonitrilo o metanol, sobre una solución acuosa tamponada. Sin embargo, fases móviles del mismo contenido en modificador orgánico y preparadas a partir de soluciones acuosas del mismo pH pero que contienen ácidos distintos como reguladores del pH, pueden presentar valores de pH significativamente diferentes.
16 p.
application/pdf
spa
Sociedad Española de Cromatografía y Técnicas Afines (SECyTA)
Reproducció del document publicat a: https://www.secyta.es/es/showjournal/190
Cromatografía y Técnicas Afines, 2009, vol. 30, num. 1, p. 15-30
(c) Subirats i Vila, Xavier et al., 2009
info:eu-repo/semantics/openAccess
Equilibri àcid-base
Cromatografia
Concentració dels ions d'hidrogen
Acid-base equilibrium
Chromatography
Hydrogen-ion concentration
Efecto de la solución amortiguadora de pH en la selectividad cromatográfica de compuestos ácido-base
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2672412016-10-18T22:29:54Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorVieira, S. P.
authorDantas, R. F.
authorEsplugas Vidal, Santiago
authorSans Mazón, Carme
authorDezotti, M.
2013-12-04T12:03:49Z
2013-12-04T12:03:49Z
2011-06
2013-12-04T12:03:50Z
1934-8932
616253
http://hdl.handle.net/2445/48288
The aim of this work was to study the influence of effluent organic matter (EfOM) on micropollutants removal by ozone and UV/H2O2. To perform the experiments, deionized water and municipal secondary effluents (SE) were artificially contaminated with atrazine (ATZ) and treated by the two proposed methods. ATZ concentration, COD and TOC were recorded along the reaction time and used to evaluate EfOM effect on the system efficiency. Results demonstrate that the presence of EfOM can significantly reduce the micropollutant removal rate due to competition of EfOM components to react with radicals and/or molecular ozone. The hydroxyl radical scavenging caused by EfOM was quantified as well as the contribution of molecular ozone and �OH radicals during the ozonation of SE. EfOM components promoted higher inhibition of ATZ oxidation by hydroxyl radicals than by molecular ozone.
15 p.
application/pdf
eng
David Publishing
Reproducció del document publicat a: http://www.davidpublishing.com/show.html?2152
Journal of Environmental Science and Engineering, 2011, vol. 5, num. 6, p. 789-798
(c) David Publishing, 2011
info:eu-repo/semantics/openAccess
Contaminació de l'aigua
Enginyeria ambiental
Ozonització
Plaguicides
Contaminants orgànics de l'aigua
Toxicitat dels medicaments
Depuració d'aigües residuals
Water pollution
Environmental engineering
Ozonization
Pesticides
Organic water pollutants
Drug toxicity
Purification of sewage
Influence of EfOM on the oxidation of micropollutants by Ozone and UV/H2O2 in secondary effluents
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2767902017-02-23T03:36:13Zhdl_2072_179323
RECERCAT (Diposit de la Recerca de Catalunya)
authorRueda Estévez, Erik
2013-08-08T11:24:32Z
2013-08-08T11:24:32Z
2013-08-08
http://hdl.handle.net/10230/20986
Treball de Fi de Grau en Criminologia i Polítiques Públiques de Prevenció. Curs 2012-2013
Tutora: Elena Larrauri Pijoan
Desde 1980 hasta 2010, la población penitenciaria no dejó de crecer. Sin embargo, desde 2010 esta tasa se está reduciendo. En este trabajo se trata de buscar una serie de explicaciones para este aumento, y para la posterior reducción. Se pone especial/natención en la entrada en vigor de la Ley Orgánica 5/2010, que supuso una extensa reforma del Código Penal. Con esta Ley Orgánica, se introdujo la posibilidad de reducir en un grado ciertas conductas contra la salud pública, en forma de subtipo atenuado./nEsto puede haber supuesto un efecto considerable sobre la reducción de las tasas de encarcelamiento. Para estudiar el efecto de este nuevo subtipo, se realiza una pequeña investigación cuantitativa sobre una muestra de sentencias por delitos contra la salud/npública. Después, se muestran los resultados y se proponen nuevas líneas de investigación.
spa
Aquest document està subjecte a una llicència Creative Commons
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by-nc-nd/3.0/es/">http://creativecommons.org/licenses/by-nc-nd/3.0/es/</a>
Treball de fi de grau – Curs 2012-2013
Presos
Presos -- Catalunya
Presos -- Espanya
Presos -- Situació legal
Posibles causas de la reducción de la población penitenciaria en España y Cataluña entre 2010 y 2013 : Efecto de la Ley Orgánica 5/2010 sobre esta reducción
info:eu-repo/semantics/bachelorThesis
oai:recercat.cat:2072/2855192017-05-23T04:48:12Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorSimón, Francesc Xavier
authorRudé i Payró, Elisabet
authorLlorens Llacuna, Joan
authorBaig, Sylvie
2013-09-06T12:11:47Z
2013-09-06T12:11:47Z
2013
2013-09-06T12:11:47Z
0011-9164
621577
http://hdl.handle.net/2445/45687
Despite the low biodegradability of seawater NOM, problems associated with biofouling are common in facilities that handle seawater. In this work, a fixed-film aerobic biofilter is proposed as an effective unit for preventing biofouling in such facilities. A packed-bed biofilter with an EBCT = 6 - 11 min was employed. The results demonstrated that the DOC is reduced by 6% and the BOD7 is reduced up to 15%. The LC-OCD analysis revealed that biofiltration abates the LMW neutrals and biopolymer fractions by 33 and 17%, respectively. However, the fractionation with UF membrane showed that the biofiltration process is able to degrade the more biodegradable compounds that have molecular weights that are greater than 1 kDa and compounds with molecular weights of less than 1 kDa. After biofiltration, the biological activity measured in terms of ATP removal was reduced by 60%. Finally, a test to evaluate the biofilm formation capacity of a water sample revealed reductions of ~94% when comparing biofiltered and non-biofiltered seawater. Therefore, a fixed-film aerobic biofiltration process could be a useful treatment for the removal of biodegradable organic matter from seawater and for improving the water quality in terms of less biofilm formation capacity.
39 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.desal.2013.01.023
Desalination, 2013, vol. 316, p. 8-16
http://dx.doi.org/10.1016/j.desal.2013.01.023
(c) Elsevier B.V., 2013
info:eu-repo/semantics/openAccess
Aigua de mar
Biodegradació
Biofilms
Contaminació de l'aigua
Enginyeria química
Seawater
Biodegradation
Biofilms
Water pollution
Chemical engineering
Study on the removal of biodegradable NOM from seawater using biofiltration
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2672822017-05-23T04:48:22Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorSentellas, Sonia
authorNúñez Burcio, Oscar
authorSaurina, Javier
2016-10-20T14:47:50Z
2016-09-30
2016-10-20T14:47:55Z
info:eu-repo/date/embargoEnd/2017-09-30
0021-8561
664394
http://hdl.handle.net/2445/102800
The determination of biogenic amines (BAs) in food products stirs up an increasing interest because of the implications in toxicological and food quality issues. Apart from these aspects, in the last years, the relevance of BAs because of some organoleptic and descriptive concerns has been pointed out by several researchers. This overview aims at revising recent advances in the determination of BAs in food samples based on liquid chromatography. In particular, papers published in the last five years have been commented. Special attention has been paid in the great possibilities of ultra-high performance liquid chromatography and high-resolution mass spectrometry. Regarding applications, apart from the determination of BAs in a wide range of food matrices, novel lines of research focused on the characterization, classification and authentication of food products based on chemometrics have also been discussed.
12 p.
application/pdf
eng
American Chemical Society, Books and Journals Division]
Versió postprint del document publicat a: http://dx.doi.org/10.1021/acs.jafc.6b02789
Journal of Agricultural and Food Chemistry, 2016, vol. 64, num. 41, p. 7667-7678
http://dx.doi.org/10.1021/acs.jafc.6b02789
(c) American Chemical Society, Books and Journals Division], 2016
info:eu-repo/semantics/embargoedAccess
Quimiometria
Cromatografia de líquids
Aliments
Chemometrics
Liquid chromatography
Food
Recent advances in the determination of biogenic amines in food samples by (U)HPLC
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2701442017-05-23T04:48:23Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorFarrés-Cebrián, M.
authorSeró, Raquel
authorSaurina, Javier
authorNúñez Burcio, Oscar
2016-12-16T13:04:15Z
2016-12-16T13:04:15Z
2016-12-08
2016-12-16T13:04:20Z
2297-8739
665772
http://hdl.handle.net/2445/104811
HPLC-UV was applied to the analysis and characterization of olive oils and other vegetable oils. A chromatographic separation on a Zorbax Eclipse XDB-C8 reversed-phase column was proposed under gradient elution, employing 0.1% formic acid aqueous solution and methanol as mobile phase, for the determination of 14 polyphenols and phenolic acids, allowing to obtain compositional profiles in less than 20 min. Acceptable sensitivity (LOD values down to 80 µg/L in the best of cases), linearity (r2 higher than 0.986), good run-to-run and day-to-day precisions (RSD values lower than 11.5%), and method trueness (relative errors lower than 6.8%) were obtained. The proposed HPLC-UV method was then applied to the analysis of 72 oil samples (47 olive oils and 27 vegetable oils including sunflower, soy, corn, and mixtures of them). Analytes were recovered by liquid-liquid extraction method employing ethanol:water 70:30 (v/v) solution and hexane as extracting and defatting solvents, respectively. HPLC-UV polyphenolic profiles using peak areas were then analysed by principal component analysis (PCA) to extract information of the most significant data contributing to the characterization and classification of olive oils against other vegetable oils, as well as among Arbequina and Picual olive oil varieties. PCA results showed a noticeable separation among olive oils and the other classes. Besides, a reasonable discrimination of olive oils as a function of fruit varieties was also encountered.
13 p.
application/pdf
eng
MDPI
Reproducció del document publicat a: https://doi.org/10.3390/separations3040033
Separations, 2016, vol. 3, num. 4, p. 33
https://doi.org/10.3390/separations3040033
cc-by (c) Farrés-Cebrián, M. et al., 2016
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by/3.0/es">http://creativecommons.org/licenses/by/3.0/es</a>
Polifenols
Oli d'oliva
Olis vegetals
Cromatografia de líquids d'alta resolució
Polyphenols
Olive oil
Vegetable oils
High performance liquid chromatography
HPLC-UV polyphenolic profiles in the classification of olive oils and other vegetable oils by principal component analysis
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2706292017-05-23T04:48:26Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorPardo, Naiara
authorVera, Alex
authorBarbosa, Sergio
authorHidalgo-Serrano, Míriam
authorNúñez Burcio, Oscar
authorSaurina, Javier
authorHernández Cassou, Santiago
authorPuignou i Garcia, Lluís
2017-01-12T15:03:52Z
2017-04-15
2017-01-12T15:03:52Z
info:eu-repo/date/embargoEnd/2018-04-15
0308-8146
664601
http://hdl.handle.net/2445/105523
HPLC-UV was applied to the analysis and characterization of fruit-based and fruit-processed products. A Kinetex C18 reversed-phase column was proposed under gradient elution for the determination of 17 polyphenols. Acceptable sensitivity (LODs below 0.16 mg/L), and good linearity (r2 higher then 0.995), precision (RSD below 6.8%), and method trueness (relative errors below 11%) were obtained. Data corresponding to polyphenolic peak areas and HPLC-UV chromatographic fingerprints were then analyzed by exploratory principal component analysis (PCA) to extract information of the most significant variables contributing to characterization and classification of analyzed samples regarding the fruit of origin. HPLC-UV chromatographic data was further treated by partial least square (PLS) regression to determine the percentages of adulteration in cranberry-fruit extracts. It was found that even mixture samples containing low percentages of adulterants could be distinguished from genuine cranberry extracts. Highly satisfactory results were obtained, with overall errors in the quantification of adulterations below 4.3%.
10 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: https://doi.org/10.1016/j.foodchem.2016.10.033
Food Chemistry, 2017, vol. 221, p. 29-38
https://doi.org/10.1016/j.foodchem.2016.10.033
cc-by-nc-nd (c) Elsevier B.V., 2017
info:eu-repo/semantics/embargoedAccess
<a href="http://creativecommons.org/licenses/by-nc-nd/3.0/es">http://creativecommons.org/licenses/by-nc-nd/3.0/es</a>
Cromatografia de líquids d'alta resolució
Polifenols
Quimiometria
High performance liquid chromatography
Polyphenols
Chemometrics
Characterization, classification and authentication of fruit-based extracts by means of HPLC-UV chromatographic fingerprints, polyphenolic profiles and chemometric methods
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2727592017-05-23T04:48:28Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorPérez-Maciá, María Ángeles
authorBringue Tomás, Roger
authorIborra Urios, Montserrat
authorTejero Salvador, Xavier
authorCunill García, Fidel
2017-02-07T12:56:14Z
2017-02-07T12:56:14Z
2016-01-01
2017-02-07T12:56:14Z
0001-1541
657758
http://hdl.handle.net/2445/106615
Kinetics of the catalytic dehydration of 1-butanol to di-n-butyl ether (DNBE) over Amberlyst 70 was investigated. Experiments were performed in liquid phase at 4 MPa and 413 463 K. Three elementary reaction mechanisms were considered: a Langmuir‐Hinselwood‐ Hougen‐Watson (LHHW) formulation; an Eley-Rideal (ER) formulation in which DNBE remains adsorbed; an ER formulation in which water remains adsorbed. Two kinetic models explain satisfactorily the dehydration of 1-butanol to DNBE: a LHHW formalism in which the surface reaction between two adjacent adsorbed molecules of 1-butanol is the rate limiting step (RLS) and where the adsorption of water is negligible, and a mechanism in which the RLS is the desorption of water being the adsorption of DNBE negligible. In both models the strong inhibiting effect of water was successfully taken into account by means of a correction factor derived from a Freundlich adsorption isotherm. Both models present similar values of apparent activation energies (122±2 kJ/mol)
15 p.
application/pdf
eng
American Institute of Chemical Engineers (AIChE)
Versió postprint del document publicat a: https://doi.org/10.1002/aic.15020
AIChE Journal, 2016, vol. 62, num. 1, p. 180-194
https://doi.org/10.1002/aic.15020
(c) American Institute of Chemical Engineers, 2016
info:eu-repo/semantics/openAccess
Resines de bescanvi iònic
Èters
Cinètica enzimàtica
Alcohols
Catàlisi
Ion exchange resins
Ethers
Enzyme kinetics
Alcohols
Catalysis
Kinetic study of 1-butanol dehydration to di-n-butyl ether over Amberlyst 70
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2815182017-05-23T04:48:30Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorMilinovic, Jelena
authorLacorte i Bruguera, Sílvia
authorRigol Parera, Anna
authorVidal Espinar, Miquel
2017-03-08T11:10:02Z
2017-03-08T11:10:02Z
2016-01-16
2017-03-08T11:10:02Z
0944-1344
655974
http://hdl.handle.net/2445/108082
The sorption behaviour of three perfluoroalkyl substances (PFASs) (perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutanesulfonic acid (PFBS)) was studied in sewage sludge samples. Sorption isotherms were obtained by varying initial concentrations of PFOS, PFOA and PFBS. The maximum values of the sorption solid-liquid distribution coefficients (Kd,max) varied by almost two orders of magnitude among the target PFASs: 140-281 mL g−1 for PFOS, 30-54 mL g−1 for PFOA and 9-18 mL g−1 for PFBS. Freundlich and linear fittings were appropriate for describing the sorption behaviour of PFASs in the sludge samples, and the derived KF and Kd,linear parameters correlated well. The hydrophobicity of the PFASs was the key parameter that influenced their sorption in sewage sludge. Sorption parameters and log(KOW) were correlated, and for PFOS (the most hydrophobic compound), pH and Ca + Mg status of the sludge controlled the variation in the sorption parameter values. Sorption reversibility was also tested from desorption isotherms, which were also linear. Desorption parameters were systematically higher than the corresponding sorption parameters (up to sixfold higher), thus indicating a significant degree of irreversible sorption, which decreased in the sequence PFOS > PFOA > PFBS
37 p.
application/pdf
eng
Springer Verlag
Versió postprint del document publicat a: https://doi.org/10.1007/s11356-015-6019-9
Environmental Science and Pollution Research, 2016, vol. 23, num. 9, p. 8339-8348
https://doi.org/10.1007/s11356-015-6019-9
(c) Springer Verlag, 2016
info:eu-repo/semantics/openAccess
Llots de depuradora
Absorció
Contaminants persistents
Sewage sludge
Absorption
Persistent pollutants
Sorption of perfluoroalkyl substances in sewage sludge
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2855202017-05-23T04:48:31Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorRuiz-Hernando, Maria
authorMartinez-Elorza, Guillermo
authorLabanda, Jordi
authorLlorens Llacuna, Joan
2013-09-17T10:30:16Z
2013-09-17T10:30:16Z
2013
2013-09-17T10:30:16Z
1385-8947
627195
http://hdl.handle.net/2445/46031
Sludges resulting from wastewater treatment processes have a characteristically high water content, which complicates handling operations such as pumping, transport and disposal. To enhance the dewatering of secondary sludge, the effect of ultrasound waves, thermal treatment and chemical conditioning with NaOH have been studied. Two features of treated sludges were examined: their rheological behavior and their dewaterability. The rheological tests consisted of recording shear stress when the shear rate increases and decreases continuously and linearly with time, and when it increases and decreases in steps. Steady-state viscosity and thixotropy were obtained from the rheological tests, and both decreased significantly in all cases with increased treatment intensity. Centrifugation of ultrasonicated and thermally treated sludges allowed the total solid content to be increased by approximately 16.2% and 17.6%, respectively. These dewatered sludges had a lower viscosity and thixotropy than the untreated sludge. In contrast, alkali conditioning barely allowed the sludge to be dewatered by centrifugation, despite decreasing its viscosity and thixotropy.
36 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.cej.2013.06.046
Chemical Engineering Journal, 2013, vol. 230, p. 102-110
http://dx.doi.org/10.1016/j.cej.2013.06.046
(c) Elsevier B.V., 2013
info:eu-repo/semantics/openAccess
Llots de depuradora
Reologia
Tractament tèrmic
Ultrasons
Sewage sludge
Rheology
Heat treatment
Ultrasonics
Dewaterability of sewage sludge by ultrasonic, thermal and chemical treatments
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2815192017-05-23T04:48:32Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorVenegas Sepúlveda, Andrea
authorRigol Parera, Anna
authorVidal Espinar, Miquel
2017-03-08T11:45:04Z
2016-07-28
2017-03-08T11:45:04Z
info:eu-repo/date/embargoEnd/2017-07-28
0944-1344
664799
http://hdl.handle.net/2445/108087
Remediation strategies using soil amendments should consider the time dependence of metal availability to identify amendments that can sustainably reduce available pollutant concentrations over time. Drying-wetting cycles were applied on amendments, soils and soil + amendment mixtures, to mimic ageing at field level and investigate its effect on extractable Cd, Cu, Ni, Pb and Zn concentrations from three contaminated soils. The amendments investigated were municipal waste organic compost and biochars. The amendments, soils and mixtures were characterised by their physicochemical properties at different ageing times. The amendments were also characterised in terms of sorption capacity for Cd and Cu. The sorption capacity and the physicochemical properties of the amendments remained constant over the period examined. When mixed with the soils, amendments, especially the compost, immediately reduced the extractable metals in the soils with low pH and acid neutralisation capacity, due to the increase in pH and buffering capacity of the mixtures. The amendments had a relatively minor impact on the metal availability concentrations for the soil with substantially high acid neutralisation capacity. The most important changes in extractable metal concentrations were observed at the beginning of the experiments, ageing having a minor effect on metal concentrations when compared with the initial effect of amendments.
30 p.
application/pdf
eng
Springer Verlag
Versió postprint del document publicat a: https://doi.org/10.1007/s11356-016-7250-8
Environmental Science and Pollution Research, 2016, vol. 23, num. 20, p. 20619-20627
https://doi.org/10.1007/s11356-016-7250-8
(c) Springer Verlag, 2016
info:eu-repo/semantics/embargoedAccess
Metalls pesants
Contaminació dels sòls
Compostos orgànics
Heavy metals
Soil pollution
Organic compounds
Effect of ageing on the availability of heavy metals in soils amended with compost and biochar: evaluation of changes in soil and amendment properties
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2832492017-05-23T04:48:35Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorLyonnais, Sébastien
authorTarrés-Soler, Aleix
authorRubio Cosials, Anna
authorCuppari, Anna
authorBrito, Reicy
authorJaumot Soler, Joaquim
authorGargallo Gómez, Raimundo
authorVilaseca Casas, Marta
authorSilva, Cristina
authorGranzham, Anton
authorTeulade-Fichou, Marie-Paule
authorEritja i Casadellà, Ramon
authorSolà, Maria
2017-03-24T18:34:33Z
2017-03-24T18:34:33Z
2017-03-09
2017-03-24T18:34:34Z
2045-2322
670356
http://hdl.handle.net/2445/108899
The ability of the guanine-rich strand of the human mitochondrial DNA (mtDNA) to form G-quadruplex structures (G4s) has been recently highlighted, suggesting potential functions in mtDNA replication initiation and mtDNA stability. G4 structures in mtDNA raise the question of their recognition by factors associated with the mitochondrial nucleoid. The mitochondrial transcription factor A (TFAM), a highmobility group (HMG)-box protein, is the major binding protein of human mtDNA and plays a critical role in its expression and maintenance. HMG-box proteins are pleiotropic sensors of DNA structural alterations. Thus, we investigated and uncovered a surprising ability of TFAM to bind to DNA or RNA G4 with great versatility, showing an affinity similar than to double-stranded DNA. The recognition of G4s by endogenous TFAM was detected in mitochondrial extracts by pull-down experiments using a G4-DNA from the mtDNA conserved sequence block II (CSBII). Biochemical characterization shows that TFAM binding to G4 depends on both the G-quartets core and flanking single-stranded overhangs. Additionally, it shows a structure-specific binding mode that differs from B-DNA, including G4- dependent TFAM multimerization. These TFAM-G4 interactions suggest functional recognition of G4s in the mitochondria.
application/pdf
eng
Nature Publishing Group
Reproducció del document publicat a: https://doi.org/10.1038/srep43992
Scientific Reports, 2017, vol. 7, num. 43992
https://doi.org/10.1038/srep43992
cc-by (c) Lyonnais, Sébastien et al., 2017
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by/3.0/es">http://creativecommons.org/licenses/by/3.0/es</a>
ADN mitocondrial
G-estructures
Àcids nucleics
Mitochondrial DNA
G-structures
Nucleic acids
The human mitochondrial transcription factor A is a versatile G-quadruplex binding protein
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2834212017-05-23T04:48:36Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorAviñó Andrés, Anna
authorDellafiore, Maria
authorGargallo Gómez, Raimundo
authorGonzález, Carlos
authorIribarren, Adolfo M.
authorMontserrat, Javier
authorEritja i Casadellà, Ramon
2017-04-19T11:23:44Z
2017-04-13
2017-04-19T11:23:44Z
info:eu-repo/date/embargoEnd/2018-04-13
1439-4227
671009
http://hdl.handle.net/2445/109785
G-quadruplex and i-motif are tetraplex structures present in telomeres and promoter regions of oncogenes. The possibility of producing nanodevices with pH-sensitive functions has triggered the interest for modified oligonucleotides with improved structural properties. We synthesized C-rich oligonucleotides carrying conformationally restricted (2'S)-2'-deoxy-2'-C-methyl-cytidine units. The effect of this modified nucleoside on the stability of intramolecular i-motifs related to vertebrate telomere was investigated by means of spectroscopic methods (UV, CD and NMR). The replacement of selected positions of the C-core by the appropriate C-modified residues induces the formation of stable intercalated tetraplexes at pHs near neutrality. The study demonstrates the possibility of enhancing the stability of i-motif by chemical modifications.
7 p.
application/pdf
eng
Wiley-VCH
Versió postprint del document publicat a: https://doi.org/10.1002/cbic.201700112
ChemBioChem, 2017
https://doi.org/10.1002/cbic.201700112
(c) Wiley-VCH, 2017
info:eu-repo/semantics/embargoedAccess
Àcids nucleics
Oligonucleòtids
G-estructures
Nucleic acids
Oligonucleotides
G-structures
Stabilization of telomeric i-motif structures by (2'S)-2'-deoxy-2'-C-methyl-cytidine residues
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2837232017-05-23T04:48:37Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorCruells Cadevall, Montserrat
authorRoca, Antoni (Roca Vallmajor)
authorEscaja Sánchez, Nuria
authorFernández González, Javier
authorGarrido Ponce, José Antonio
authorGiménez Farreras, Jaume
authorLlauradó i Tarragó, Montserrat
authorRodríguez Raurell, Laura
authorBernad Marcos, Josep Oriol
authorEscobar Arias, Carla Salomé
authorLópez Vinent, Núria
authorSagristá Gratovil, M. Lluïsa
authorNavarro Aragay, Carme
authorCompanyó Beltrán, Ramón
2017-04-24T11:56:16Z
2017-04-24T11:56:16Z
2017-01
2017-04-24T11:56:16Z
2014-5349
670761
http://hdl.handle.net/2445/109998
In scientific and technical degrees, the opinion of the final employers on the given subjects is really important. For this reason, the Quality Committee (CQ) of the Faculty of Chemistry of the University of Barcelona prepared a survey for chemical, engineering and pharmaceutical companies asking about the academic training required by the companies. The survey consists of nine sections including items related to laboratory operations, chemical processes, calculation methods, management systems (quality, environment and safety) or general management information. In addition, at the end of each section, a question inquires the companies about the competences shown by students in the items of the section. The results were compared with that of a similar survey carried out in 2007. The scores obtained, between 2 and 3, for all the items (score: 1, not important; 2, unimportant; 3, important; 4, very important), show that companies accept the training given to our students and the competences achieved by them. However, according to their opinion, it is possible to improve this training, especially in the subjects related to management (time, information, environment, quality, safety, etc.). Therefore, surveys are a good tool for the evaluation of the training achieved in our degrees and, consequently, for improving degrees and the teaching task, according the Quality Management System implemented in the Faculty of Chemistry.
20 p.
application/pdf
eng
Omnia Science
Reproducció del document publicat a: https://doi.org/10.3926/jotse.232
Journal of Technology and Science Education, 2017, vol. 7, num. 1, p. 80-99
https://doi.org/10.3926/jotse.232
cc-by (c) Cruells Cadevall, Montserrat et al., 2017
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by/3.0/es">http://creativecommons.org/licenses/by/3.0/es</a>
Competències professionals
Qualitat de l'ensenyament
Control de qualitat
Avaluació de sistemes educatius
Educació superior
Vocational qualifications
Educational quality
Quality control
Educational systems evaluation
Higher education
The surveys to the companies: a tool for the improvement of degrees
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2838792017-05-23T04:48:38Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorPell i Lorente, Albert
authorMárquez, Anna
authorLópez Sánchez, José Fermín
authorRubio i Rovira, Roser
authorBarbero Castro, Mercedes
authorStegen, Susana
authorQueirolo, Fabrizio
authorDíaz-Palma, Paula
2017-04-26T12:54:55Z
2017-04-26T12:54:55Z
2013-01
2017-04-26T12:54:55Z
0045-6535
621866
http://hdl.handle.net/2445/110162
This study reports data on arsenic speciation in two green algae species (Cladophora sp. and Chara sp.) and in five aquatic plants (Azolla sp., Myriophyllum aquaticum, Phylloscirpus cf. desserticola, Potamogeton pectinatus, Ruppia filifolia and Zannichellia palustris) from the Loa River Basin in the Atacama Desert (northern Chile). Arsenic content was measured by Mass Spectrometry coupled with Inductively Coupled Plasma (ICP-MS), after acidic digestion. Liquid Chromatography coupled to ICP-MS was used for arsenic speciation, using both anionic and cationic chromatographic exchange systems. Inorganic arsenic compounds were the main arsenic species measured in all samples. The main arsenic species in the extracts of freshwater algae and plants were arsenite and arsenate, whereas glycerol-arsenosugar (gly-sug), dimethylarsinic acid (DMA) and methylarsonic acid (MA) were present only as minor constituents. Of the samples studied, algae species accumulated more arsenic than aquatic plants. Total arsenic content ranged from 182 to 11,100 and from 20 to 248 mg As kg-1 (d.w.) in algae and freshwater plants, respectively. In comparison with As concentration in water samples, there was hyper-accumulation (>0.1% d.w.) in Cladophora sp.
9 p.
application/pdf
eng
Elsevier Ltd
Versió postprint del document publicat a: https://doi.org/10.1016/j.chemosphere.2012.08.028
Chemosphere, 2013, vol. 90, num. 2, p. 556-564
https://doi.org/10.1016/j.chemosphere.2012.08.028
(c) Elsevier Ltd, 2013
info:eu-repo/semantics/openAccess
Arsènic
Algues
Plantes aquàtiques
Arsenic
Algae
Aquatic plants
Occurrence of arsenic species in algae and freshwater plants of an extreme arid region in northern Chile, the Loa River Basin
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2845632017-05-23T04:48:40Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorMans Teixidó, Claudi, 1948-
2017-05-10T14:13:31Z
2017-05-10T14:13:31Z
2015
2017-05-10T14:13:31Z
2013-2298
659443
http://hdl.handle.net/2445/110777
El propòsit d'aquesta comunicació és presentar l'experiència de l'autor com a tutor d'alumnes de l'ensenyament d'Enginyeria Química de la Universitat de Barcelona, i presentar un instrument que el signant denomina la TFC, la Tutoria de Final de Carrera, com a eina per a ajudar l'alumne a enfocar de manera pragmàtica i realista la darrera etapa dels seus estudis de segon cicle i fer el pas cap a l'etapa posterior en les seves múltiples facetes. Els objectius de l'activitat són reduir la incertesa de l'alumne en el moment de prendre decisions decisives per al seu futur personal i professional, donar-li autoestima i confiança, subministrar-li de forma estructurada i significativa informació sobre el món laboral i de postgrau, ajudar-lo a descobrir les pròpies aptituds i limitacions, i donar-li confiança sobre les seves possibilitats. Aquest instrument consisteix en una sessió en grup, seguida d'una tutoria individualitzada amb l'objectiu de facilitar l'orientació de l'alumne en la seva decisió sobre l'orientació futura de la seva vida professional. A part del plantejament general del tema, s'explicita el desenvolupament d'un currículum basat en competències, com a exemple del progrés de l'alumne al passar per la tutoria. Els resultats són una major satisfacció i autoestima per part de l'alumne, una superior eficàcia en el procés de pas d'alumne a preprofessional, i una superior confiança en les pròpies possibilitats.
9 p.
application/pdf
cat
Universitat de Barcelona
Reproducció del document publicat a: https://doi.org/10.1344/RIDU2015.7.3
RIDU: Revista d'Innovació Docent Universitària, 2015, num. 7, p. 20-28
https://doi.org/10.1344/RIDU2015.7.3
cc-by (c) Mans Teixidó, Claudi, 1948-, 2015
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by/3.0/es">http://creativecommons.org/licenses/by/3.0/es</a>
Tutoria (Ensenyament)
Currículums (Ensenyament)
Competències professionals
Tutoring (Teaching)
Curricula (Courses of study)
Vocational qualifications
La TFC: la Tutoria de Final de Carrera
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2855212017-05-23T04:48:43Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorArmelin, Elaine
authorMartí, Mireia
authorRudé i Payró, Elisabet
authorLabanda, Jordi
authorLlorens Llacuna, Joan
authorAlemán, Carlos
2013-09-18T08:45:04Z
2013-09-18T08:45:04Z
2006
2013-09-18T08:45:04Z
0300-9440
542371
http://hdl.handle.net/2445/46105
We propose a simple rheological model to describe the thixotropic behavior of paints, since the classical hysteresis area, which is usually used, is not enough to evaluate thixotropy. The model is based on the assumption that viscosity is a direct measure of the structural level of the paint. The model depends on two equations: the Cross-Carreau equation to describe the equilibrium viscosity and a second order kinetic equation to express the time dependence of viscosity. Two characteristic thixotropic times are differentiated: one for the net structure breakdown, which is defined as a power law function of shear rate, and an other for the net structure buildup, which is not dependent on the shear rate. The knowledge of both kinetic processes can be used to improve the quality and applicability of paints. Five representative commercial protective marine paints are tested. They are based on chlorinated rubber, acrylic, alkyd, vinyl, and epoxy resins. The temperature dependence of the rheological behavior is also studied with the temperature ranging from 5 ºC to 35 ºC. It is found that the paints exhibit both shear thinning and thixotropic behavior. The model fits satisfactorily the thixotropy of the studied paints. It is also able to predict the thixotropy dependence on temperature. Both viscosity and the degree of thixotropy increase as the temperature decreases.
23 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.porgcoat.2006.09.002
Progress in Organic Coatings, 2006, vol. 57, num. 3, p. 229-235
http://dx.doi.org/10.1016/j.porgcoat.2006.09.002
(c) Elsevier B.V., 2006
info:eu-repo/semantics/openAccess
Reologia
Tixotropia
Histèresi
Temperatura
Pintura (Producte químic)
Rheology
Thixotropy
Hysteresis
Temperature
Paint
A simple model to describe the thixotropic behavior of paints.
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2855222017-05-23T04:48:44Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorGómez, Francisco
authorQuintana, Robert
authorMartínez de Ilarduya, Antxon
authorRudé i Payró, Elisabet
authorMuñoz-Guerra, Sebastián
2013-09-18T11:20:26Z
2013-09-18T11:20:26Z
2005
2013-09-18T11:20:26Z
0887-624X
521682
http://hdl.handle.net/2445/46110
A series of poly(butylene terephthalate) copolyesters containing 5-tert-butyl isophthalate units up to 50%-mole, as well as the homopolyester entirely made of these units, were prepared by polycondensation from the melt. The microstructure of the copolymers was determined by NMR to be at random for the whole range of compositions. The effect exerted by the 5-tert-butyl isophthalate units on thermal, tensile and gas transport properties was evaluated. Both Tm and crystallinity as well as the mechanical moduli were found to decrease steadily with copolymerization whereas Tg increased and the polyesters became more brittle. Permeability and solubility sligthly increased also with the content in substituted units whereas the diffusion coefficient remained practically constant. For the homopolyester poly(5-tert-butyl isophthalate), all these properties were found to deviate significantly from the general trend displayed by copolyesters suggesting that a different chain mode of packing in the amorphous phase is likely adopted in this case.
22 p.
application/pdf
eng
Wiley
Versió preprint del document publicat a: http://dx.doi.org/10.1002/pola.20477
Journal of Polymer Science Part A: Polymer Chemistry, 2005, vol. 43, num. 1, p. 92-100
http://dx.doi.org/10.1002/pola.20477
(c) Wiley, 2005
info:eu-repo/semantics/openAccess
Copolímers
Polièsters
Permeabilitat
Propietats tèrmiques
Propietats mecàniques
Propietats òptiques
Copolymers
Polyesters
Permeability
Thermal properties
Mechanical properties
Optical properties
Poly(butylene terephthalate-co-5-tert-butyl isophthalate) Copolyesters: Synthesis, Characterization and Properties
info:eu-repo/semantics/article
info:eu-repo/semantics/submittedVersion
oai:recercat.cat:2072/2672342017-05-23T04:48:45Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorCurcó Cantarell, David
authorZanuy Gomara, David
authorAlemán, Carlos
authorMuñoz-Guerra, Sebastián
authorRudé i Payró, Elisabet
2013-09-18T12:02:22Z
2013-09-18T12:02:22Z
2003-10
2013-09-18T12:02:23Z
1525-7797
507396
http://hdl.handle.net/2445/46111
Monte Carlo (MC) simulations have been used to study the structure of an intermediate thermal phase of poly(R-octadecyl ç,D-glutamate). This is a comblike poly(ç-peptide) able to adopt a biphasic structure that has been described as a layered arrangement of backbone helical rods immersed in a paraffinic pool of polymethylene side chains. Simulations were performed at two different temperatures (348 and 363 K), both of them above the melting point of the paraffinic phase, using the configurational bias MC algorithm. Results indicate that layers are constituted by a side-by-side packing of 17/5 helices. The organization of the interlayer paraffinic region is described in atomistic terms by examining the torsional angles and the end-to-end distances for the octadecyl side chains. Comparison with previously reported comblike poly(â-peptide)s revealed significant differences in the organization of the alkyl side chains.
9 p.
application/pdf
eng
American Chemical Society
Versió postprint del document publicat a: http://dx.doi.org/10.1021/bm025702q
Biomacromolecules, 2002, vol. 4, num. 1, p. 87-95
http://dx.doi.org/10.1021/bm025702q
(c) American Chemical Society , 2002
info:eu-repo/semantics/openAccess
Polímers
Mètode de Montecarlo
Macromolècules
Models moleculars
Temperatura
Polymers
Monte Carlo method
Macromolecules
Molecular models
Temperature
Comblike poly(a-alkyl g glutamate)s: computer simulation studies of an intermediate thermal phase.
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2177232017-05-23T04:48:46Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorBenabou, Sanae
authorFerreira Aguilera, Rubén
authorAviñó Andrés, Anna
authorGonzález, Carlos
authorLyonnais, Sébastien
authorSolà Vilarrubias, Maria
authorEritja i Casadellà, Ramon
authorJaumot Soler, Joaquim
authorGargallo Gómez, Raimundo
2013-09-19T11:07:40Z
2013-09-19T11:07:40Z
2013-09-06
2013-09-19T11:07:40Z
0304-4165
628171
http://hdl.handle.net/2445/46204
Cytosine-and guanine-rich regions of DNA are capable of forming complex structures named i-motifs and G-quadruplexes, respectively. In the present study the solution equilibria at nearly physiological conditions of a 34 -bases long cytosine-rich sequence and its complementary guanin e-rich strand corresponding to the first intron of the n-mycgene were studied. Both sequences , not yet studied, contain a 12 - base tract capable of forming stable hairpins inside the i-motif and G-quadruplex structures, respectively ...
50 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.bbagen.2013.08.028
Biochimica et Biophysica Acta-General Subjects, 2013
http://dx.doi.org/10.1016/j.bbagen.2013.08.028
(c) Elsevier B.V., 2013
info:eu-repo/semantics/openAccess
ADN
RNA
Àcids nucleics
Anàlisi multivariable
Cromatografia
DNA
RNA
Nucleic acids
Multivariate analysis
Chromatography
Solution equilibria of cytosine- and guanine-rich sequences near the promoter region of the n-myc gene that contain stable hairpins within lateral loops
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2855232017-05-23T04:48:48Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorLlorens Llacuna, Joan
authorRudé i Payró, Elisabet
authorMarcos Hernández, Rosa Maria
2013-09-27T06:57:33Z
2013-09-27T06:57:33Z
2003
2013-09-27T06:57:34Z
0032-3861
507397
http://hdl.handle.net/2445/46383
This article describes a method for determining the polydispersity index Ip2=Mz/Mw of the molecular weight distribution (MWD) of linear polymeric materials from linear viscoelastic data. The method uses the Mellin transform of the relaxation modulus of a simple molecular rheological model. One of the main features of this technique is that it enables interesting MWD information to be obtained directly from dynamic shear experiments. It is not necessary to achieve the relaxation spectrum, so the ill-posed problem is avoided. Furthermore, a determinate shape of the continuous MWD does not have to be assumed in order to obtain the polydispersity index. The technique has been developed to deal with entangled linear polymers, whatever the form of the MWD is. The rheological information required to obtain the polydispersity index is the storage G′(ω) and loss G″(ω) moduli, extending from the terminal zone to the plateau region. The method provides a good agreement between the proposed theoretical approach and the experimental polydispersity indices of several linear polymers for a wide range of average molecular weights and polydispersity indices. It is also applicable to binary blends.
36 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/S0032-3861(03)00022-3
Polymer, 2003, vol. 44, num. 5, p. 1741-1750
http://dx.doi.org/10.1016/S0032-3861(03)00022-3
(c) Elsevier B.V., 2003
info:eu-repo/semantics/openAccess
Polímers
Reologia
Viscoelasticitat
Pesos moleculars
Macromolècules
Polymers
Rheology
Viscoelasticity
Molecular weights
Macromolecules
Polydispersity index from linear viscoelastic data: Unimodal and bimodal linear polymer melts
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2855242017-05-23T04:48:48Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorKint, Darwin, P. R.
authorRudé i Payró, Elisabet
authorLlorens Llacuna, Joan
authorMuñoz-Guerra, Sebastián
2013-10-04T10:00:57Z
2013-10-04T10:00:57Z
2002
2013-10-04T10:00:57Z
0032-3861
507395
http://hdl.handle.net/2445/46684
The influence of incorporating 5-tert-butyl isophthalic units (tBI) in the polymer chain of poly(ethylene terephthalate) (PET) on the crystallization behavior, crystal structure, and tensile and gas transport properties of this polyester was evaluated. Random poly(ethyleneterephthalate-co-5-tert-butyl isophthalate) copolyesters (PETtBI) containing between 5 and 40 mol% of tBI units were examined. Isothermal crystallization studies were performed on amorphous glassy films at 120 8C and on molten samples at 200 8C by means of differential scanning calorimetry. Furthermore, the non-isothermal crystallization behavior of the copolyesters was investigated. It was observed that both crystallinity and crystallization rate of the PETtBI copolyesters tend to decrease largely with the comonomeric content, except for the copolymer containing 5 mol% of tBI units, which crystallized faster than PET. Fiber X-ray diffraction patterns of the semicrystalline PETtBI copolyesters proved that they adopt the same triclinic crystal structure as PET with the comonomeric units being excluded from the crystalline phase. Although PETtBI copolyesters became brittle for higher contents in tBI, the tensile modulus and strength of PET were barely affected by copolymerization. The ncorporation of tBI units slightly increased the permeability of PET, but copolymers containing up to 20 mol% of the comonomeric units were still able to present barrier properties.
18 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/S0032-3861(02)00715-2
Polymer, 2002, vol. 43, num. 26, p. 7529-7537
http://dx.doi.org/10.1016/S0032-3861(02)00715-2
(c) Elsevier B.V., 2002
info:eu-repo/semantics/openAccess
Cristal·lització
Estructura cristal·lina (Sòlids)
Propietats mecàniques
Permeabilitat
Tereftalat de polietilè
Crystallization
Layer structure (Solids)
Mechanical properties
Permeability
Polyethylene terephthalate
Crystallization and properties of poly(ethylene terephtalate) copolymers containing 5-tert-butyl isophtalic units
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2203762017-05-23T04:48:49Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorFunes Collado, Virginia
authorMorell García, Albert
authorRubio i Rovira, Roser
authorLópez Sánchez, José Fermín
2013-11-22T12:39:25Z
2013-11-22T12:39:25Z
2013-06-29
2013-11-22T12:39:25Z
0308-8146
629265
http://hdl.handle.net/2445/47995
Selenium is recognised as an essential micronutrient for humans and animals. One of the main sources of selenocompounds in the human diet is vegetables. Therefore, this study deals with the Se species present in different edible sprouts grown in Se-enriched media. We grew alfalfa, lentil and soy in a hydroponic system amended with soluble salts, containing the same proportion of Se, in the form of Se(VI) and Se(IV). Total Se in the sprouts was determined by acidic digestion in a microwave system and by ICP/MS. Se speciation was carried out by enzymatic extraction (Protease XIV) and measured by LC-ICP/MS. The study shows that the Se content of plants depends on the content in the growth culture, and that part of the inorganic Se was biotransformed mainly into SeMet. These results contribute to our understanding of the uptake of inorganic Se and its biotransformation by edible plants.
20 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.foodchem.2013.06.090
Food Chemistry, 2013, vol. 141, num. 4, p. 3738-3743
http://dx.doi.org/10.1016/j.foodchem.2013.06.090
(c) Elsevier B.V., 2013
info:eu-repo/semantics/openAccess
Seleni
Plantes
Aminoàcids
Enzims
Llavors
Química dels aliments
Nutrició
Selenium
Plants
Amino acids
Enzymes
Seeds
Food chemistry
Nutrition
Study of selenocompounds from selenium-enriched culture of edible sprouts
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2203772017-05-23T04:48:52Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorFunes Collado, Virginia
authorMorell García, Albert
authorRubio i Rovira, Roser
authorLópez Sánchez, José Fermín
2013-11-22T12:54:47Z
2013-11-22T12:54:47Z
2013-09-28
2013-11-22T12:54:47Z
0304-4238
629267
http://hdl.handle.net/2445/47996
As a constituent of selenoproteins, selenium (Se) is considered an essential element for human health.The main way that Se enters the body is via the consumption of vegetables, whose concentration of thiselement depends on soil Se content. We grew cabbage, lettuce, chard and parsley, in peat enriched in Seby means of the additive Selcote Ultra®and Na2SeO3and Na2SeO4. Total Se in plants was determinedby acidic digestion and Se speciation by an enzymatic extraction. Both were measured by ICP/MS. Theconcentration ranges were between 0.1 mg Se kg−1and 30 mg Se kg−1for plants grown in Selcote Ultra®media, and between 0.4 mg Se kg−1and 1606 mg Se kg−1for those grown in peat enriched with Se sodiumsalts. We found Se (IV), Se (VI) and SeMet in all the extracts. Peat fortified with Selcote Ultra®gave slightlyhigher Se concentration than natural content values. For plants grown with selenium sodium salts, Secontent increases with the Se added and part of the inorganic Se was converted mainly to SeMet. A highSe fortification can damage or inhibit plant growth. Cabbage showed the greatest tolerance to Se.
23 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.scienta.2013.09.052
Scientia Horticulturae, 2013, vol. 164, p. 428-433
http://dx.doi.org/10.1016/j.scienta.2013.09.052
(c) Elsevier B.V., 2013
info:eu-repo/semantics/openAccess
Seleni
Plantes comestibles
Torba
Nutrició
Enzims
Aminoàcids
Selenium
Edible plants
Peat
Nutrition
Enzymes
Amino acids
Selenium uptake by edible plants from enriched peat.
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2208502017-05-23T04:48:54Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorLlorente-Mirandes, Toni
authorCalderon, Josep
authorCentrich, F.
authorRubio i Rovira, Roser
authorLópez Sánchez, José Fermín
2013-12-03T09:35:03Z
2013-12-03T09:35:03Z
2013-10-05
2013-12-03T09:35:03Z
0308-8146
629268
http://hdl.handle.net/2445/48244
The present study arose from the need to determine inorganic arsenic (iAs) at low levels in cereal-based food. Validated methods with a low limit of detection (LOD) are required to analyse these kinds of food. An analytical method for the determination of iAs, methylarsonic acid (MA) and dimethylarsinic acid (DMA) in cereal-based food and infant cereals is reported. The method was optimised and validated to achieve low LODs. Ion chromatography-inductively coupled plasma mass spectrometry (LC-ICPMS) was used for arsenic speciation. The main quality parameters were established. To expand the applicability of the method, different cereal products were analysed: bread, biscuits, breakfast cereals, wheat flour, corn snacks, pasta and infant cereals. The total and inorganic arsenic content of 29 cereal-based food samples ranged between 3.7-35.6 and 3.1-26.0 microg As kg-1, respectively. The present method could be considered a valuable tool for assessing inorganic arsenic contents in cereal-based foods.
33 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.foodchem.2013.09.138
Food Chemistry, 2013, vol. 147, p. 377-385
http://dx.doi.org/10.1016/j.foodchem.2013.09.138
(c) Elsevier B.V., 2013
info:eu-repo/semantics/openAccess
Arsènic
Compostos inorgànics
Cereals (Aliment)
Alimentació infantil
Química dels aliments
Espectrometria de masses de plasma acoblat inductivament
Arsenic
Inorganic compounds
Grain (feed)
Child nutrition
Food chemistry
Inductively coupled plasma mass spectrometry
A need for determination of arsenic species at low levels in cereal-based food and infant cereals. Validation of a method by LC-ICPMS.
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2212802017-05-23T04:48:56Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorPell i Lorente, Albert
authorKokkinis, Giannis
authorMalea, Paraskea
authorPergantis, Spiros A.
authorRubio i Rovira, Roser
authorLópez Sánchez, José Fermín
2013-12-17T08:17:40Z
2013-12-17T08:17:40Z
2013-09-07
2013-12-17T08:17:41Z
0045-6535
629266
http://hdl.handle.net/2445/48483
The content of total arsenic and arsenic compounds in the dominant seaweed species in the Thermaikos Gulf, Northern Aegean Sea was determined in samples collected in different seasons. Total arsenic was determined by acid digestion followed by ICP-MS. Arsenic speciation was analyzed by water extraction followed by LC-ICP-MS. Total arsenic concentrations in the seaweeds ranged from 1.39 to 55.0 mg kg- 1. Cystoseira species and Codium fragile showed the highest total As contents, while Ulva species (U. intestinalis, U. rigida,U. fasciata) had the lowest Arsenosugars, the most common arsenic species in seaweeds, were found in all samples, and glycerol-arsenosugar was the most common form; however, phosphate-arsenosugar and sulfate-arsenosugar were also present. Inorganic arsenic was measured in seven algae species and detected in another. Arsenate was the most abundant species in Cystoseira barbata (27.0 mg kg- 1). Arsenobetaine was measured in only one sample. Methylated arsenic species were measured at very low concentrations. The information should contribute to further understanding the presence of arsenic compounds in dominant seaweeds from the Thermaikos Gulf.
29 p.
application/pdf
eng
Elsevier Ltd
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.chemosphere.2013.08.003
Chemosphere, 2013, vol. 93, num. 9, p. 2187-2194
http://dx.doi.org/10.1016/j.chemosphere.2013.08.003
(c) Elsevier Ltd, 2013
info:eu-repo/semantics/openAccess
Arsènic.
Algues marines.
Toxicologia alimentària.
Contaminació del mar.
Egea (Mar)
Arsenic.
Marine algae.
Food toxicology.
Marine pollution.
Aegean Sea.
LC-ICP-MS analysis of arsenic compounds in dominant seaweeds from the Thermaikos Gulf (Northern Aegean Sea, Greece).
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2217642017-05-23T04:48:58Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorCalmet, D.
authorJerome, S.
authorAmeon, R.
authorBombard, A.
authorForte, M.
authorFournier, M.
authorHerranz, M.
authorKwakman, P.
authorLlauradó i Tarragó, Montserrat
authorTokonami, S.
2014-01-07T10:19:09Z
2014-01-07T10:19:09Z
2013
2014-01-07T10:19:09Z
0020-708X
617442
http://hdl.handle.net/2445/48694
Water is vital to humans and each of us needs at least 1.5 L of safe water a day to drink. Beginning as long ago as 1958 the World Health Organization (WHO) has published guidelines to help ensure water is safe to drink. Focused from the start on monitoring radionuclides in water, and continually cooperating with WHO, the International Standardization Organization (ISO) has been publishing standards on radioactivity test methods since 1978. As reliable, comparable and"fit for purpose" results are an essential requirement for any public health decision based on radioactivity measurements, international standards of tested and validated radionuclide test methods are an important tool for production of such measurements. This paper presents the ISO standards already published that could be used as normative references by testing laboratories in charge of radioactivity monitoring of drinking water as well as those currently under drafting and the prospect of standardized fast test methods in response to a nuclear accident.
17 p.
application/pdf
eng
Elsevier
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.apradiso.2013.03.052
International Journal of Applied Radiation and Isotopes, 2013, vol. 81, p. 21 - 25
http://dx.doi.org/10.1016/j.apradiso.2013.03.052
(c) Elsevier, 2013
info:eu-repo/semantics/openAccess
Normes ISO
Aigua
Radioactivitat
Aigua potable
Accidents nuclears
ISO Standards
Water
Radioactivity
Drinking water
Nuclear accidents
ISO standars on test methods for water radioactivity monitoring
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2229642017-05-23T04:48:59Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorHermo Outeiral, Ma. del Pilar
authorSaurina, Javier
authorBarbosa Torralbo, José
authorBarrón Bueno, Dolores
2014-01-30T09:59:32Z
2014-01-30T09:59:32Z
2014
2014-01-30T09:59:32Z
0308-8146
632234
http://hdl.handle.net/2445/49273
The performance of high resolution accurate mass spectrometry (HRMS) operating in full scan MS mode was investigated for the quantitative determination of amoxicillin (AMX) as well as qualitative analysis of metabolomic profiles in tissues of medicated chickens. The metabolomic approach was exploited to compile analytical information on changes in the metabolome of muscle, kidney and liver from chickens subjected to a pharmacological program with AMX. Data consisting of m/z features taken throughout the entire chromatogram were extracted and filtered to be treated by Principal Component Analysis. As a result, it was found that medicated and non-treated animals were clearly clustered in distinct groups. Besides, the multivariate analysis revealed some relevant mass features contributing to this separation. In this context, recognizing those potential markers of each chicken class was a priority research for both metabolite identification and, obviously, evaluation of food quality and health effects associated to food consumption.
35 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.foodchem.2013.12.080
Food Chemistry, 2014, vol. 153, p. 405-413
http://dx.doi.org/10.1016/j.foodchem.2013.12.080
(c) Elsevier B.V., 2014
info:eu-repo/semantics/openAccess
Amoxicil·lina
Anàlisi multivariable
Espectrometria de masses
Gallines
Qualitat dels aliments
Amoxicillin
Multivariate analysis
Mass spectrometry
Hens
Food quality
High-resolution mass spectrometry applied to the study of metabolome modifications in various chicken tissues after amoxicillin administration
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2229652017-05-23T04:49:00Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorHermo Outeiral, Ma. del Pilar
authorGómez-Rodríguez, P.
authorBarbosa Torralbo, José
authorBarrón Bueno, Dolores
2014-01-30T11:10:05Z
2014-01-30T11:10:05Z
2013
2014-01-30T11:10:05Z
0731-7085
623453
http://hdl.handle.net/2445/49280
The aim of this study was to identity metabolites and transformation products (TPs) in chicken muscle from amoxicillin (AMX), cephapirin (PIR) and ceftiofur (TIO), which are antibiotics of the β-lactam family. Liquid chromatography coupled to quadrupole time-of-flight (QqTOF) mass spectrometry was utilized due to its high resolution, high mass accuracy and MS/MS capacity for elemental composition determination and structural elucidation. Amoxicilloic acid (AMA) and amoxicillin diketopiperazine (DKP) were found as transformation products from AMX. Desacetylcephapirin (DAC) was detected as a metabolite of PIR. Desfuroylceftiofur (DFC) and its conjugated compound with cysteine (DFC-S-Cys) were detected as a result of TIO in contact with chicken muscle tissue. The metabolites and transformation products were also monitored during the in vivo AMX treatment and slaughtering period. It was found that two days were enough to eliminate AMX and associated metabolites/transformation products after the end of administration.
30 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.jpba.2013.07.023
Journal of Pharmaceutical and Biomedical Analysis, 2013, vol. 85, p. 169-178
http://dx.doi.org/10.1016/j.jpba.2013.07.023
(c) Elsevier B.V., 2013
info:eu-repo/semantics/openAccess
Amoxicil·lina
Antibiòtics
Gallines
Músculs
Antibiòtics betalactàmics
Metabòlits
Amoxicillin
Antibiotics
Hens
Muscles
Beta lactam antibiotics
Metabolites
Metabolomic assays of amoxicillin, cephapirin and ceftiofur in chicken muscle. Application to treated chicken samples by liquid chromatography quadrupole time-of-flight mass spectrometry
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2229662017-05-23T04:49:01Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorJiménez-Díaz, Inmaculada
authorHermo Outeiral, Ma. del Pilar
authorBallesteros, Óscar
authorZafra-Gómez, Alberto
authorBarrón Bueno, Dolores
authorBarbosa Torralbo, José
authorNavalón, Alberto
2014-01-30T11:49:54Z
2014-01-30T11:49:54Z
2013
2014-01-30T11:49:54Z
0009-5893
621475
http://hdl.handle.net/2445/49283
This work presents a comparison between three analytical methods developed for the simultaneous determination of eight quinolones regulated by the European Union (marbofloxacin, ciprofloxacin, danofloxacin, enrofloxacin, difloxacin, sarafloxacin, oxolinic acid and flumequine) in pig muscle, using liquid chromatography with fluorescence detection (LC-FD), liquid chromatography-mass spectrometry (LC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS). The procedures involve an extraction of the quinolones from the tissues, a step for clean-up and preconcentration of the analytes by solid-phase extraction and a subsequent liquid chromatographic analysis. The limits of detection of the methods ranged from 0.1 to 2.1 ng g−1 using LC-FD, from 0.3 to 1.8 using LC-MS and from 0.2 to 0.3 using LC-MS/MS, while inter- and intra-day variability was under 15 % in all cases. Most of those data are notably lower than the maximum residue limits established by the European Union for quinolones in pig tissues. The methods have been applied for the determination of quinolones in six different commercial pig muscle samples purchased in different supermarkets located in the city of Granada (south-east Spain).
16 p.
application/pdf
eng
Springer Verlag
Versió postprint del document publicat a: http://dx.doi.org/10.1007/s10337-013-2435-5
Chromatographia, 2013, vol. 76, num. 11-12, p. 707-713
http://dx.doi.org/10.1007/s10337-013-2435-5
(c) Springer Verlag, 2013
info:eu-repo/semantics/openAccess
Cromatografia de líquids
Fluorescència
Espectrometria de masses
Quinolones
Porc
Músculs
Liquid chromatography
Fluorescence
Mass spectrometry
Quinolone antibacterial agents
Swine
Muscles
Comparison of three analytical methods for the determination of quinolones in pig muscle samples
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2270092017-05-23T04:49:02Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorJunza Martínez, Alexandra
authorBarbosa, S.
authorCodony Salcedo, Rafael
authorJubert, A.
authorBarbosa Torralbo, José
authorBarrón Bueno, Dolores
2014-03-21T09:44:57Z
2015-02-05T23:01:54Z
2014-02-05
2014-03-21T07:36:59Z
0021-8561
633710
http://hdl.handle.net/2445/52728
The presence of residues of antibiotics, metabolites, and thermal transformation products (TPs), produced during thermal treatment to eliminate pathogenic microorganisms in milk, could represent a risk for people. Cow"s milk samples spiked with enrofloxacin (ENR), ciprofloxacin (CIP), difloxacin (DIF), and sarafloxacin (SAR) and milk samples from cows medicated with ENR were submitted to several thermal treatments. The milk samples were analyzed by liquid chromatography-mass spectrometry (LC-MS) to find and identify TPs and metabolites. In this work, 27 TPs of 4 quinolones and 24 metabolites of ENR were found. Some of these compounds had been reported previously, but others were characterized for the first time, including lactose-conjugated CIP, the formamidation reaction for CIP and SAR, and hydroxylation or ketone formation to produce three different isomers for all quinolones studied.
46 p.
application/pdf
eng
American Chemical Society, Books and Journals Division]
Versió postprint del document publicat a: http://dx.doi.org/10.1021/jf405554z
Journal of Agricultural and Food Chemistry, 2014, vol. 62, num. 8, p. 2008-2021
http://dx.doi.org/10.1021/jf405554z
(c) American Chemical Society, Books and Journals Division], 2014
info:eu-repo/semantics/openAccess
Metabòlits
Quinolones
Llet
Cromatografia de líquids
Espectrometria de masses
Antibiòtics
Tractament tèrmic
Metabolites
Quinolone antibacterial agents
Milk
Liquid chromatography
Mass spectrometry
Antibiotics
Heat treatment
Identification of metabolites and thermal transformation products of quinolones in raw cow milk by liquid chromatography coupled to high resolution mass spectrometry.
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2855282017-05-23T04:49:03Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorDíaz, Francesc (Díaz González)
authorGavaldà, Josefina
authorKawall, J. G.
authorKeffer, J. F.
authorGiralt, Francesc
2012-05-03T12:36:03Z
2012-05-03T12:36:03Z
1983-12
0021-8979
14192
http://hdl.handle.net/2445/24893
An experimental investigation of a two-dimensional turbulent wake behind a spinning cylinder at Re=9000 is carried out to determine the influence of the rotation on the initial development of the flow. Spectral analysis of the velocity data measured in the near wake shows that for peripheral velocities up to the value of the free¿stream velocity, a distinct Kármán vortex activity exists within the wake, whereas for greater peripheral velocities, the Kármán activity deteriorates and disappears for values in excess of twice the free-stream velocity.
7 p.
application/pdf
eng
American Institute of Physics
Reproducció del document publicat a: http://dx.doi.org/10.1063/1.864127
Physics of Fluids, 1983, vol. 26, núm. 12, p. 3454-3460
http://dx.doi.org/10.1063/1.864127
(c) American Institute of Physics, 1983
info:eu-repo/semantics/openAccess
Mecànica de fluids
Plasma (Gasos ionitzats)
Turbulència
Velocitat
Espectroscòpia
Fluid mechanics
Plasma (Ionized gases)
Turbulence
Speed
Spectrum analysis
Vortex shedding from a spinning cylinder
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2394412017-05-23T04:49:05Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorFons Castells, Jordi
authorZapata García, Daniel
authorTent Petrus, Joana Ma.
authorLlauradó i Tarragó, Montserrat
2014-04-02T10:30:07Z
2014-04-02T10:30:07Z
2013
2014-04-02T10:30:08Z
0265-931X
637116
http://hdl.handle.net/2445/53191
The determination of gross alpha, gross beta and 226Ra activity in natural waters is useful in a wide range of environmental studies. Furthermore, gross alpha and gross beta parameters are included in international legislation on the quality of drinking water [Council Directive 98/83/EC].1 In this work, a low-background liquid scintillation counter (Wallac, Quantulus 1220) was used to simultaneously determine gross alpha, gross beta and 226Ra activity in natural water samples. Sample preparation involved evaporation to remove 222Rn and its short-lived decay daughters. The evaporation process concentrated the sample ten-fold. Afterwards, a sample aliquot of 8 mL was mixed with 12 mL of Ultima Gold AB scintillation cocktail in low-diffusion vials. In this study, a theoretical mathematical model based on secular equilibrium conditions between 226Ra and its short-lived decay daughters is presented. The proposed model makes it possible to determine 226Ra activity from two measurements. These measurements also allow determining gross alpha and gross beta simultaneously. To validate the proposed model, spiked samples with different activity levels for each parameter were analysed. Additionally, to evaluate the model's applicability in natural water, eight natural water samples from different parts of Spain were analysed. The eight natural water samples were also characterised by alpha spectrometry for the naturally occurring isotopes of uranium (234U, 235U and 238U), radium (224Ra and 226Ra), 210Po and 232Th. The results for gross alpha and 226Ra activity were compared with alpha spectrometry characterization, and an acceptable concordance was obtained.
5 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.jenvrad.2013.01.017
Journal of Environmental Radioactivity, 2013, vol. 125, p. 56-60
http://dx.doi.org/10.1016/j.jenvrad.2013.01.017
(c) Elsevier B.V., 2013
info:eu-repo/semantics/openAccess
Radioactivitat
Mostreig mediambiental
Escintil·ladors líquids
Contaminació de l'aigua
Espanya
Radioactivity
Environmental sampling
Liquid scintillators
Water pollution
Spain
Simultaneous determination of gross alpha, gross beta and Ra-226 in natural water by liquid scintillation counting.
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2280122017-05-23T04:49:06Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorLlorente-Mirandes, Toni
authorBarbero Castro, Mercedes
authorRubio i Rovira, Roser
authorLópez Sánchez, José Fermín
2014-04-09T08:09:42Z
2014-04-09T08:09:42Z
2014-11-01
2014-04-09T08:09:43Z
0308-8146
638708
http://hdl.handle.net/2445/53383
The present study reports arsenic speciation analysis in edible Shiitake (Lentinula edodes) products. The study focused on the extraction, and accurate quantification of inorganic arsenic (iAs), the most toxic form of arsenic, which was selectively separated and determined using anion exchange LC-ICPMS. A wide variety of edible Shiitake products (fresh mushrooms, food supplements, canned and dehydrated) were purchased and analysed. A cultivated Shiitake grown under controlled conditions was also analysed. The extraction method showed satisfactory extraction efficiencies (>90%) and column recoveries (>85%) for all samples. Arsenic speciation revealed that iAs was the major As compound up to 1.38 mg As per kg dm (with a mean percentage of 84% of the total arsenic) and other organoarsenicals were found as minor species. Shiitake products had high proportions of iAs and therefore should not be ignored as potential contributors to dietary iAs exposure in populations with a high intake of Shiitake products.
35 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org./10.1016/j.foodchem.2014.02.081
Food Chemistry, 2014, vol. 158, num. 1, p. 207-215
http://dx.doi.org/10.1016/j.foodchem.2014.02.081
(c) Elsevier B.V., 2014
info:eu-repo/semantics/openAccess
Arsènic
Bolets comestibles
Toxicologia alimentària
Química organometàl·lica
Arsenic
Edible mushrooms
Food toxicology
Organometallic chemistry
Occurrence of inorganic arsenic in edible Shiitake (Lentinula edodes) products
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2855302017-05-23T04:49:11Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorMay Masnou, Anna
authorRibó i Besolí, Jordi
authorPorras Rodríguez, Montserrat
authorMaestro Garriga, Alicia
authorGonzález Azón, María del Carmen
authorGutiérrez González, José María, 1953-
2015-02-11T08:08:39Z
2015-02-11T08:08:39Z
2014
2015-02-11T08:08:40Z
0009-2509
646607
http://hdl.handle.net/2445/62743
We examine the scale invariants in the preparation of highly concentrated w/o emulsions at different scales and in varying conditions. The emulsions are characterized using rheological parameters, owing to their highly elastic behavior. We first construct and validate empirical models to describe the rheological properties. These models yield a reasonable prediction of experimental data. We then build an empirical scale-up model, to predict the preparation and composition conditions that have to be kept constant at each scale to prepare the same emulsion. For this purpose, three preparation scales with geometric similarity are used. The parameter N¿D^α, as a function of the stirring rate N, the scale (D, impeller diameter) and the exponent α (calculated empirically from the regression of all the experiments in the three scales), is defined as the scale invariant that needs to be optimized, once the dispersed phase of the emulsion, the surfactant concentration, and the dispersed phase addition time are set. As far as we know, no other study has obtained a scale invariant factor N¿Dα for the preparation of highly concentrated emulsions prepared at three different scales, which covers all three scales, different addition times and surfactant concentrations. The power law exponent obtained seems to indicate that the scale-up criterion for this system is the power input per unit volume (P/V).
30 p.
application/pdf
eng
Elsevier Ltd
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.ces.2014.03.004
Chemical Engineering Science, 2014, vol. 111, p. 410-420
http://dx.doi.org/10.1016/j.ces.2014.03.004
(c) Elsevier Ltd, 2014
info:eu-repo/semantics/openAccess
Reologia
Emulsions
Enginyeria química
Similitud (Geometria)
Rheology
Emulsions
Chemical engineering
Scale-up model obtained from the rheological analysis of highly concentrated emulsions prepared at three scales
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2855322017-05-23T04:49:12Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorKudela, Damien
authorSmith, Stephanie A.
authorMay Masnou, Anna
authorBraun, Gary B.
authorPallaoro, Alessia
authorNguyen, Chi K.
authorChuong, Tracy T.
authorNownes, Sara
authorAllen, Riley
authorParker, Nicholas R.
authorRashidi, Hooman H.
authorMorrissey, James H.
authorStucky, Galen D.
2015-02-11T09:34:09Z
2016-01-29T23:01:31Z
2015-01-29
2015-02-11T09:34:11Z
0044-8249
646608
http://hdl.handle.net/2445/62752
We present a silica nanoparticle (SNP) functionalized with polyphosphate (polyP) that accelerates the natural clotting process of the body. SNPs initiate the contact pathway of the blood-clotting system; short-chain polyP accelerates the common pathway by the rapid formation of thrombin, which enhances the overall blood-clotting system, both by accelerating fibrin generation and by facilitating the regulatory anticoagulation mechanisms essential for hemostasis. Analysis of the clotting properties of bare SNPs, bare polyP, and polyP-functionalized SNPs in plasma demonstrated that the attachment of polyP to SNPs to form polyP-SNPs creates a substantially enhanced synergistic effect that lowers clotting time and increases thrombin production at low concentrations. PolyP-SNP even retains its clotting function at ambient temperature. The polyP-SNP system has the potential to significantly improve trauma-treatment protocols and outcomes in hospital and prehospital settings.
5 p.
application/pdf
eng
Wiley-VCH
Versió postprint del document publicat a: http://doi.org/10.1002/ange.201409639
Angewandte Chemie, 2015, vol. 127, num. 3
http://dx.doi.org/10.1002/ange.201409639
(c) Wiley-VCH, 2015
info:eu-repo/semantics/openAccess
Silici
Nanopartícules
Silicats
Ferides i lesions
Hemorràgia
Silicon
Nanoparticles
Silicates
Wounds and injuries
Hemorrhage
Clotting activity of polyphosphate-functionalized silica nanoparticles
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2855332017-05-23T04:49:12Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorMay Masnou, Anna
authorSalvadó i Rovira, Joan
authorTorras, Carles
authorMontané i Calaf, Daniel
2015-02-11T10:06:27Z
2015-02-11T10:06:27Z
2010
2015-02-11T10:06:27Z
1385-8947
625735
http://hdl.handle.net/2445/62753
The conversion of glycerol in supercritical water (SCW) was studied at 510-550 °C and a pressure of 350 bars using both a bed of inert and non-porous ZrO2 particles (hydrothermal experiments), and a bed of a 1% Ru/ZrO2 catalyst. Experiments were conducted with a glycerol concentration of 5 wt% in a continuous isothermal fixed-bed reactor at a residence time between 2 and 10 s. Hydrothermolysis of glycerol formed water-soluble products such as acetaldehyde, acetic acid, hydroxyacetone and acrolein, and gases like H2, CO and CO2. The catalyst enhanced the formation of acetic acid, inhibited the formation of acrolein, and promoted gasification of the glycerol decomposition products. Hydrogen and carbon oxides were the main gases produced in the catalytic experiments, with minor amounts of methane and ethylene. Complete glycerol conversion was achieved at a residence time of 8.5 s at 510 °C, and at around 5 s at 550 °C with the 1 wt% Ru/ZrO2 catalyst. The catalyst was not active enough to achieve complete gasification since high yields of primary products like acetic acid and acetaldehyde were still present. Carbon balances were between 80 and 60% in the catalytic experiments, decreasing continuously as the residence time was increased. This was attributed partially to the formation of methanol and acetaldehyde, which were not recovered and analyzed efficiently in our set-up, but also to the formation of carbon deposits. Carbon deposition was not observed on the catalyst particles but on the surface of the inert zirconia particles, especially at high residence time. This was related to the higher concentration of acetic acid and other acidic species in the catalytic experiments, which may polymerize to form tar-like carbon precursors. Because of carbon deposition, hydrogen yields were significantly lower than expected; for instance at 550 °C the hydrogen yield potential was only 50% of the stoichiometric value.
25 p.
application/pdf
eng
University College London, Faculty of Mathematical and Physical Sciences, Department of Mathematics
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.cej.2010.04.005
Chemical Engineering Journal, 2010, vol. 160, num. 2, p. 751-759
http://dx.doi.org/10.1016/j.cej.2010.04.005
(c) University College London, Faculty of Mathematical and Physical Sciences, Department of Mathematics, 2010
info:eu-repo/semantics/openAccess
Biotecnologia
Gasificació de la biomassa
Hidrogen
Producció
Ruteni
Catalitzadors
Biotechnology
Biomass gasification
Hydrogen
Production
Ruthenium
Catalysts
Catalytic gasification of glycerol in supercritical water
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2855352017-05-23T04:49:13Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorMaestro Garriga, Alicia
authorGonzález, C.
authorGutiérrez González, José María, 1953-
2012-05-03T10:55:01Z
2012-05-03T10:55:01Z
2002
0148-6055
510595
http://hdl.handle.net/2445/24847
The rheological behavior of hydrophobically modified hydroxyethyl cellulose HMHEC, an associative thickener, was studied and compared with that of hydrophobically modified ethoxylated urethanes HEURs and nonassociative celluloses. In contrast to HEURs, a simple Maxwell model does not fit the linear viscoelastic behavior of HMHEC. Differences are attributed to the stiffness and comb structure of HMHEC. A generalized Maxwell model with a logarithmic distribution of relaxation times is proposed, and another parameter that includes Rouse-like relaxation is added to fit behavior at high frequencies. Four parameters are needed to describe HMHEC viscoelasticity: a mean relaxation time, lM ; its corresponding standard deviation, s; a plateau modulus, GN ; and a viscosity at infinite frequency, h ` . Satisfactory fitting is obtained for all concentrations and temperatures in the range of frequencies studied. The sharp increase of GN with concentration indicates loop-to-bridge transitions. Temperature does not influence GN , since the reduction in the number density of elastically effective chains caused by Brownian motion masks the direct effect of temperature. The dependence of lM on temperature follows the Arrhenius equation, as does the relaxation time of HEURs, but it does not change with concentration, presumably because the comb structure of HMHEC prevents the formation of long superchains.
17 p.
application/pdf
eng
The Society of Rheology
Reproducció del document publicat a: http://dx.doi.org/10.1122/1.1427910
Journal of Rheology, 2002, vol. 46, p. 127-143
http://dx.doi.org/10.1122/1.1427910
(c) The Society of Rheology, 2002
info:eu-repo/semantics/openAccess
Reologia
Cel·lulosa
Viscoelasticitat
Polímers
Solucions (Química)
Rheology
Cellulose
Viscoelasticity
Polymers
Solution (Chemistry)
Rheological behavior of hydrophobically modified hydroxyethyl cellulose solutions: A linear viscoelastic model
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2855372017-05-23T04:49:15Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorMay Masnou, Anna
authorAramaki, Kenji
authorGutiérrez González, José María, 1953-
2015-02-11T12:41:17Z
2015-02-11T12:41:17Z
2011-02-02
2015-02-11T12:41:17Z
0743-7463
625736
http://hdl.handle.net/2445/62786
This article reports the phase behavior determi- nation of a system forming reverse liquid crystals and the formation of novel disperse systems in the two-phase region. The studied system is formed by water, cyclohexane, and Pluronic L-121, an amphiphilic block copolymer considered of special interest due to its aggregation and structural proper- ties. This system forms reverse cubic (I2) and reverse hexagonal (H2) phases at high polymer concentrations. These reverse phases are of particular interest since in the two-phase region, stable high internal phase reverse emulsions can be formed. The characterization of the I2 and H2 phases and of the derived gel emulsions was performed with small-angle X-ray scattering (SAXS) and rheometry, and the influence of temperature and water content was studied. TheH2 phase experimented a thermal transition to an I2 phase when temperature was increased, which presented an Fd3m structure. All samples showed a strong shear thinning behavior from low shear rates. The elasticmodulus (G0) in the I2 phase was around 1 order of magnitude higher than in theH2 phase. G0 was predominantly higher than the viscousmodulus (G00). In the gel emulsions,G0 was nearly frequency-independent, indicating their gel type nature. Contrarily to water-in-oil (W/O) normal emulsions, in W/I2 and W/H2 gel emulsions, G0, the complex viscosity (|η*|), and the yield stress (τ0) decreased with increasing water content, since the highly viscous microstructure of the con- tinuous phase was responsible for the high viscosity and elastic behavior of the emulsions, instead of the volumefraction of dispersed phase and droplet size. A rheological analysis, in which the cooperative flow theory, the soft glass rheology model, and the slip plane model were analyzed and compared, was performed to obtain one single model that could describe the non-Maxwellian behavior of both reverse phases and highly concentrated emulsions and to characterize their microstructure with the rheological properties.
40 p.
application/pdf
eng
American Chemical Society
Versió postprint del document publicat a: http://dx.doi.org/10.1021/la104539q
Langmuir, 2011, vol. 27, num. 6, p. 2286-2298
http://dx.doi.org/10.1021/la104539q
(c) American Chemical Society , 2011
info:eu-repo/semantics/openAccess
Col·loides
Polímers
Gels (Farmàcia)
Emulsions
Reologia
Colloids
Polymers
Gels (Pharmacy)
Emulsions
Rheology
Phase behavior and rheological analysis of reverse liquid crystals and W/I2, W/H2 gel emulsions using an amphiphilic block copolymer.
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2467122017-05-23T04:49:15Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorEsteban i Cortada, Miquel
authorSahuquillo Estrugo, Àngels
2015-02-17T15:39:20Z
2015-02-17T15:39:20Z
2014-12-15
2015-02-17T15:39:20Z
0717-9324
646785
http://hdl.handle.net/2445/63048
The Erasmus Mundus Master in Quality in Analytical Laboratories (EMQAL) is a two-year Joint Master Degree. The course is funded by the European Commission through the Erasmus Mundus Programme, providing a number of attractive scholarships for European and non-European students. EMQAL prepares professionals for analytical laboratories, focusing on laboratory management and quality systems, along with complementing their technical knowledge. The EMQAL aims at training students in the most relevant issues concerning quality systems and management in analytical laboratories, and to become an expert in: Quality management, Analytical methods and Data Analysis. EMQAL promotes mobility. The students will attend one academic year of lectures in one of the European universities of the EMQAL consortium, and a 12 months master thesis at other European university, with the possibility to spend three-months in one of the non-EU partners. The language of instruction and examination is English. Further information is available at www.emqal.org.
4 p.
application/pdf
eng
Sociedad Chilena de Química
Reproducció del document publicat a: http://dx.doi.org/10.4067/S0717-97072014000400019
Journal of the Chilean Chemical Society, 2014, vol. 59, num. 4, p. 2721-2724
http://dx.doi.org/10.4067/S0717-97072014000400019
cc-by-nc (c) Sociedad Chilena de Química, 2014
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by-nc/3.0/es">http://creativecommons.org/licenses/by-nc/3.0/es</a>
Estudis de màster
Beques d'investigació
Laboratoris
Científics
Qualitat total
Masters degrees
Research grants
Laboratories
Scientists
Total quality management
ERASMUS (Programa)
EMQAL: Erasmus Mundus Master in Quality in Analytical Laboratories
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2855382017-05-23T04:49:17Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorBacardit Peñarroya, Jordi
authorSans Mazón, Carme
authorSeminago, Ramon
authorEsplugas Vidal, Santiago
2015-05-25T10:45:58Z
2015-05-25T10:45:58Z
2010-01-25
2015-05-25T10:45:58Z
0888-5885
575831
http://hdl.handle.net/2445/65627
In a previous work, a hybrid system consisting of an advanced oxidation process (AOP) named Photo-Fenton (Ph-F) and a fixed bed biological treatment operating as a sequencing batch biofilm reactor (SBBR) was started-up and optimized to treat 200 mg·L-1 of 4-chlorophenol (4-CP) as a model compound. In this work, studies of reactor stability and control as well as microbial population determination by molecular biology techniques were carried out to further characterize and control the biological reactor. Results revealed that the integrated system was flexible and even able to overcome toxic shock loads. Oxygen uptake rate (OUR) in situ was shown to be a valid tool to control the SBBR operation, to detect toxic conditions to the biomass, and to assess the recovery of performance. A microbial characterization by 16S rDNA sequence analysis reveals that the biological population was varied, although about 30% of the bacteria belonged to the Wautersia genus.
5 p.
application/pdf
eng
American Chemical Society
Versió postprint del document publicat a: http://dx.doi.org/10.1021/ie901642u
Industrial & Engineering Chemistry Research, 2010, vol. 49, num. 15, p. 6972-6976
http://dx.doi.org/10.1021/ie901642u
(c) American Chemical Society , 2010
info:eu-repo/semantics/openAccess
Aigües residuals
Depuració d'aigües residuals
Sistemes de control biològic
Sewage
Purification of sewage
Biological control systems
Characterization and Control Strategies of an Integrated Chemical-Biological System for the Remediation of Toxic Pollutants in Wastewater: A case of study
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2855392017-05-23T04:49:18Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorGiménez Farreras, Jaume
authorBayarri Ferrer, Bernardí
authorGonzález, O.
authorMalato, S.
authorPeral, J.
authorEsplugas Vidal, Santiago
2015-06-05T14:55:37Z
2015-06-05T14:55:37Z
2014-12-31
2015-06-05T14:55:37Z
1420-3049
652585
http://hdl.handle.net/2445/65744
Today, environmental impact associated with pollution treatment is a matter of great concern. A method is proposed for evaluating environmental risk associated with Advanced Oxidation Processes (AOPs) applied to wastewater treatment. The method is based on the type of pollution (wastewater, solids, air or soil) and on materials and energy consumption. An Environmental Risk Index (E), constructed from numerical criteria provided, is presented for environmental comparison of processes and/or operations. The Operation Environmental Risk Index (EOi) for each of the unit operations involved in the process and the Aspects Environmental Risk Index (EAj) for process conditions were also estimated. Relative indexes were calculated to evaluate the risk of each operation (E/NOP) or aspect (E/NAS) involved in the process, and the percentage of the maximum achievable for each operation and aspect was found. A practical application of the method is presented for two AOPs: photo-Fenton and heterogeneous photocatalysis with suspended TiO2 in Solarbox. The results report the environmental risks associated with each process, so that AOPs tested and the operations involved with them can be compared.
16 p.
application/pdf
eng
MDPI
Reproducció del document publicat a: http://dx.doi.org/10.3390/molecules20010503
Molecules, 2014, vol. 20, num. 1, p. 503-518
http://dx.doi.org/10.3390/molecules20010503
cc-by (c) Giménez Farreras, Jaume et al., 2014
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by/3.0/es">http://creativecommons.org/licenses/by/3.0/es</a>
Avaluació del risc ambiental
Avaluació d'impacte ambiental
Environmental risk assessment
Environmental impact analysis
A Comparison of the Environmental Impact of Different AOPs: Risk Indexes
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2855402017-05-23T04:49:20Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorMay-Masnou, Anna
authorPorras Rodríguez, Montserrat
authorMaestro Garriga, Alicia
authorGonzález, Carme
authorGutiérrez González, José María, 1953-
2015-07-13T12:43:29Z
2015-07-13T12:43:29Z
2013
2015-07-13T12:43:29Z
0009-2509
637000
http://hdl.handle.net/2445/66318
Reverse high internal phase ratio emulsions (HIPRE) are prepared with the system water/Span80/dodecane to identify the influence of the process variables on droplet size and polydispersity, and to study the influence of the process scale-up. After discussing the most common scale invariants used in emulsification processes, we prepare emulsions at two different scales following a complete factorial experimental design. Using the empirical models obtained with the statistical analysis of the results, we determine the scale invariants for the system. Results from a previous study indicated that the scale invariant for the preparation of HIPRE could be the stirring rate. However, the results obtained in this work show that the scale invariant, based on droplet size, could change depending on the conditions of emulsification. Only when the stirring rate is high enough (> 1500 rpm), or when the surfactant-to-oil ratio is high and the total addition time low, the scale invariant is indeed the stirring rate. The elevated shear stress inside the mixer when the stirring rate is high is responsible of the small droplet size obtained on both scales. However, for other values of the process variables, the scale-invariant can be expressed as N¿D^a, where 0 < a < 0.5, and depends on other two factors: the addition flow rate of dispersed phase or addition time, and the surfactant-to-oil ratio. We propose a methodology to determine these scale invariants and to calculate the threshold values of surfactant-to-oil ratio and addition flow rate from which the stirring rate is the scale invariant (when a → 0).
33 p.
application/pdf
eng
Elsevier Ltd
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.ces.2013.07.033
Chemical Engineering Science, 2013, vol. 101, num. ---, p. 721-730
http://dx.doi.org/10.1016/j.ces.2013.07.033
(c) Elsevier Ltd, 2013
info:eu-repo/semantics/openAccess
Emulsions
Emulsions
Scale invariants in the preparation of reverse high internal phase ratio emulsions
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2540952017-05-23T04:49:20Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorAstefanei, Alina
authorNúñez Burcio, Oscar
authorGalcerán Huguet, M. Teresa
2015-09-09T11:10:30Z
2015-09-09T11:10:30Z
2015-03-25
2015-09-09T11:10:30Z
0003-2670
648984
http://hdl.handle.net/2445/66853
A prominent sector of nanotechnology is occupied by a class of carbon-based nanoparticles known as fullerenes. Fullerene particle size and shape impact in how easily these particles are transported into and throughout the environment and living tissues. Currently, there is a lack of adequate methodology for their size and shape characterisation, identification and quantitative detection in environmental and biological samples. The most commonly used methods for their size measurements (aggregation, size distribution, shape, etc.), the effect of sampling and sample treatment on these characteristics and the analytical methods proposed for their determination in complex matrices are discussed in this review. For the characterisation and analysis of fullerenes in real samples, different analytical techniques including microscopy, spectroscopy, flow field-flow fractionation, electrophoresis, light scattering, liquid chromatography and mass spectrometry have been reported. The existing limitations and knowledge gaps in the use of these techniques are discussed and the necessity to hyphenate complementary ones for the accurate characterisation, identification and quantitation of these nanoparticles is highlighted.
69 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.aca.2015.03.025
Analytica Chimica Acta, 2015, vol. 882, p. 1-21
http://dx.doi.org/10.1016/j.aca.2015.03.025
cc-by-nc-nd (c) Elsevier B.V., 2015
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by-nc-nd/3.0/es">http://creativecommons.org/licenses/by-nc-nd/3.0/es</a>
Ful·lerens
Fullerenes
Characterisation and determination of fullerenes: a critical review
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2544132017-05-23T04:49:22Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorFélez, Cristina
authorMolet, Anna
authorNúñez Burcio, Oscar
2015-09-18T11:22:21Z
2015-09-18T11:22:21Z
2015-07-20
2015-09-18T11:22:21Z
2227-9075
653733
http://hdl.handle.net/2445/66944
A field-amplified sample injection-micellar electrokinetic chromatography (FASI-MEKC) method for the determination of 14 benzophenones (BPs) in a food simulant used in migration studies of food packaging materials was developed, allowing almost baseline separation in less than 21 min. The use of a 10 mM sodium dodecyl sulfate (SDS) solution as sample matrix was mandatory to achieve FASI enhancement of the analyzed BPs. A 21- to 784-fold sensitivity enhancement was achieved with FASI-MEKC, obtaining limits of detection down to 5.1<br>68.4 µg/L, with acceptable run-to-run precisions (RSD values lower than 22.3%) and accuracy (relative errors lower than 21.0%). Method performance was evaluated by quantifying BPs in the food simulant spiked at 500 µg/L (bellow the established specific migration limit for BP (600 µg/L) by EU legislation). For a 95% confidence level, no statistical differences were observed between found and spiked concentrations (probability at the confidence level, p value, of 0.55), showing that the proposed FASI-MEKC method is suitable for the analysis of BPs in food packaging migration studies at the levels established by EU legislation.
20 p.
application/pdf
eng
MDPI
Reproducció del document publicat a: http://dx.doi.org/10.3390/chromatography2030452
Chromatography, 2015, vol. 2(3), p. 452-471
http://dx.doi.org/10.3390/chromatography2030452
cc-by (c) Félez, Cristina et al., 2015
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by/3.0/es">http://creativecommons.org/licenses/by/3.0/es</a>
Cromatografia
Envasament d'aliments
Chromatography
Food packaging
Field-Amplified Sample Injection-Micellar Electrokinetic Chromatography for the Determination of Benzophenones in Food Simulants
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2855422017-05-23T04:49:25Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorMaestro Garriga, Alicia
authorGonzález García, Ma. Concepción
authorGutiérrez González, José María, 1953-
2012-05-03T10:58:33Z
2012-05-03T10:58:33Z
2002
0148-6055
510596
http://hdl.handle.net/2445/24848
Steady state viscosity and thixotropy of hydrophobically modified hydroxyethyl cellulose HMHEC and nonassociative cellulose water solutions are studied. Although all the samples are shear thinning, only the HMHEC is thixotropic, since the migration of hydrophobes to micelles is controlled by diffusion. The Cross model fits steady state curves. The Mewis model, a phenomenological model that proposes that the rate of change of viscosity when the shear rate is suddenly changed is related to the difference between the steady state and current values of viscosity raised to an exponent, fits structure construction experiments when the exponent, n, is estimated to be around 2. The Newtonian assumption used by Mewis cannot be used here, however. This seems to be related to the fact that the thickening is due to bridged micelle formation, which is a slow process, and also to topological constraints and entanglements, which are rapid processes. The kinetic parameter was redefined to kn in order to make it independent of initial conditions. So, kn depends only on how the shear affects the structure. kn reaches a plateau at shear rates too low to produce structure destruction and decreases at higher shear rates.
13 p.
application/pdf
eng
The Society of Rheology
Reproducció del document publicat a: http://dx.doi.org/10.1122/1.1516789
Journal of Rheology, 2002, vol. 46, p. 1445-1457
http://dx.doi.org/10.1122/1.1516789
(c) The Society of Rheology, 2002
info:eu-repo/semantics/openAccess
Reologia
Viscositat
Revestiments
Tixotropia
Rheology
Viscosity
Coatings
Thixotropy
Shear thinning and thixotropy of HMHEC and HEC water solutions
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2580582017-05-23T04:49:25Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorPandey, Satyaprakash
authorAgarwala, Prachi
authorJayaraj, Gopal G.
authorGargallo Gómez, Raimundo
authorMaiti, Souvik
2016-02-05T12:12:09Z
2016-11-10T23:01:28Z
2015-11-10
2016-02-05T12:12:10Z
0006-2960
655395
http://hdl.handle.net/2445/69282
Biological role for existence of overlapping structures in RNA is possible yet remains very less explored. G-rich tracts of RNA form G-quadruplexes while GC-rich sequences prefer stem-loop structures. Equilibrium between alternate structures within RNA may occur and influence its functionality. We tested equilibrium between G-quadruplex and stem-loop structure in RNA and its effect on biological processes using pre-miRNA as a model system. Dicer enzyme recognizes canonical stem-loop structures in pre-miRNA to produce mature miRNAs. Deviation from stem-loop leads to deregulated mature miRNA levels, providing readout of existence of alternate structure per se G-quadruplex mediated structural interference in miRNA maturation. In vitro analysis using beacon and Dicer cleavage assays indicated that mature miRNA levels depend on relative amounts of K+ and Mg2+ ions suggesting an ion-dependent structural shift. Further in cellulo studies with and without TmPyP4 (RNA G-quadruplex destabilizer) demonstrated that miRNA biogenesis is modulated by G-quadruplex-stem-loop equilibrium in a subset of pre-miRNAs. Our combined analysis thus provides evidence for formation of non-canonical G-quadruplexes in competition with canonical stem-loop structure inside the cell and its effect on miRNA maturation in a comprehensive manner.
12 p.
application/pdf
eng
American Chemical Society
Versió postprint del document publicat a: http://dx.doi.org/10.1021/acs.biochem.5b00574
Biochemistry, 2015, vol. 54, num. 48, p. 7067-7078
http://dx.doi.org/10.1021/acs.biochem.5b00574
(c) American Chemical Society , 2015
info:eu-repo/semantics/openAccess
RNA
Porfirines
RNA
Porphyrins
RNA stem-loop to G-quadruplex equilibrium controls mature miRNA production inside the cell
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2685172017-05-23T04:49:31Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorBadia i Córcoles, Jordi Hug
authorFité Piquer, Carles
authorBringue Tomás, Roger
authorRamírez Rangel, Eliana
authorCunill García, Fidel
2016-03-14T10:03:31Z
2017-02-08T23:01:26Z
2016-02-08
2016-03-14T10:03:36Z
0021-9568
658053
http://hdl.handle.net/2445/96442
The chemical equilibrium of the liquid-phase syntheses of 2-methoxy-2-methylpropane (MTBE), 2-ethoxy-2-methylpropane (ETBE), 2-methyl-2-propoxypropane (PTBE), and 1-tert-butoxybutane (BTBE) by reaction of isobutene with methanol, ethanol, 1-propanol, and 1-butanol, respectively, has been studied. Four different ion exchange resins as the catalysts, and two different reactor systems, namely, a batch reactor and a setup of tubular reactors, were used. Temperature and pressure were in the range 313-383 K and 1.5-2.0 MPa, respectively. MTBE and ETBE synthesis reactions experiments were carried out mainly to validate the reliability of the reaction systems. Experiments in PTBE and BTBE etherifications allowed estimating thermodynamic properties for those reactions and involved species, namely, molar standard enthalpy and entropy changes of reaction and molar enthalpy change of formation of the four ethers. A comparison of estimated reaction thermodynamic values among the homologous series of linear alcohols, and with results quoted in the literature, when available, has been made.
47 p.
application/pdf
eng
American Chemical Society
Versió postprint del document publicat a: http://dx.doi.org/10.1021/acs.jced.5b00557
Journal of Chemical and Engineering Data, 2016, vol. 61, num. 3, p. 1054-1064
http://dx.doi.org/10.1021/acs.jced.5b00557
(c) American Chemical Society , 2016
info:eu-repo/semantics/openAccess
Èters
Alcohols
Equilibri químic
Termodinàmica
Ethers
Alcohols
Chemical equilibrium
Thermodynamics
Thermodynamic analysis of the experimental equilibria for the liquid-phase etherification of isobutene with C1 to C4 linear primary alcohols
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2855442017-05-23T04:49:32Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorMay-Masnou, Anna
authorStébé, Marie José
authorBlin, Jean Luc
2016-04-14T10:44:43Z
2016-12-23T23:01:13Z
2015-12-23
2016-04-14T10:44:48Z
1434-1948
660403
http://hdl.handle.net/2445/97404
We report here the synthesis of different kinds of hierarchical porous silica materials by using mixtures of an amphiphilic block copolymer (Pluronic P123) and a nonionic fluorinated surfactant. In particular, we have taken advantage of the difference in polarities between the two compounds to design dual-mesoporous materials through the cooperative templating mechanism (CTM). We have undertaken a complete study of this system by varying the composition of the mixed micelles and the synthesis conditions. We have shown that both the dual-mesoporosity and the mesopore ordering are favored when materials are prepared with fluorine-rich and P123-rich micelles. However, when the P123-rich micelles predominate, the mesostructure is less organized and the dual-porosity depends on the P123 content. In addition, concentrated emulsions were formed by incorporating perfluorodecalin (PFD) in the surfactant mixture, and hierarchical macro-mesoporous materials were prepared by combining the CTM and the emulsion templating mechanism.
23 p.
application/pdf
eng
Wiley-VCH
Versió postprint del document publicat a: http://dx.doi.org/10.1002/ejic.201501168
European Journal of Inorganic Chemistry, 2015
http://dx.doi.org/10.1002/ejic.201501168
(c) Wiley-VCH, 2015
info:eu-repo/semantics/openAccess
Agents tensioactius
Materials porosos
Silici
Emulsions
Surface active agents
Porous materials
Silicon
Emulsions
Hierarchical meso-mesoporous and macro-mesoporous silica templated by mixtures of polyoxyethylene fluoroalkyl ether and triblock copolymer
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2612852017-05-23T04:49:35Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorPara, B. V. (Bianca Veronica)
authorNúñez Burcio, Oscar
authorMoyano Morcillo, Encarnación
authorGalcerán Huguet, M. Teresa
2016-04-29T11:18:30Z
2016-04-29T11:18:30Z
2006-05-30
2016-04-29T11:18:36Z
0173-0835
536299
http://hdl.handle.net/2445/98051
Conditions for the separation and determination of benzalkonium chloride (BAC) homologues by CE with UV-detection and CE coupled to MS (IT) using electrospray as ionization source were established. The separation was performed using fused-silica capillaries of 50 μm id and 100 mM acetic acid-ammonium acetate buffer solution at pH 4.5 with 80% of ACN as carrier electrolyte. CE-MS coupling parameters were optimized and methanol-10 mM acetic acid (90:10 v/v) was selected as sheath liquid. Detection limits, based on an S/N of 3:1, were calculated, and values between 0.8 and 1.3 mg/L with CE-ESI/MS and around 0.5 mg/L with CE-ESI-MS/MS, using hydrodynamic injection (15 s, 3.5 kPa), were obtained. Good run-to-run and day-to-day precisions on concentration were achieved with RSDs lower than 8%. Quantitative analysis was carried out by the internal standard method and the calibration curves showed good linearities (r2>0.98). The CE-ESI-MS/MS method was successfully applied to the analysis of BAC in different ophthalmic solutions, allowing the direct determination, identification and confirmation of the BAC homologues presented in these samples.
26 p.
application/pdf
eng
Wiley-VCH
Versió postprint del document publicat a: http://dx.doi.org/10.1002/elps.200500716
Electrophoresis, 2006, vol. 27, num. 11, p. 2225-2232
http://dx.doi.org/10.1002/elps.200500716
(c) Wiley-VCH, 2006
info:eu-repo/semantics/openAccess
Electroforesi capil·lar
Capillary electrophoresis
Análisis of Benzalkonium chloride by capillary electrophoresis-electrospray-Tandem mass spectrometry
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2613322017-05-23T04:49:36Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorGallart Ayala, Hèctor
authorNúñez Burcio, Oscar
authorMoyano Morcillo, Encarnación
authorGalcerán Huguet, M. Teresa
2016-05-02T12:11:59Z
2016-05-02T12:11:59Z
2010-11-27
2016-05-02T12:12:04Z
0021-9673
582866
http://hdl.handle.net/2445/98160
A fast method of liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) was developed for the analysis of eleven UV ink photoinitiators in packaged food. Chromatographic separation was achieved in a pentafluorophenylpropyl (PFPP) column at 5ºC and acetonitrile:25 mM formic acid-ammonium formate (pH 2.7) in gradient elution. To reduce sample treatment, a QuEChERS (quick, easy, cheap, effective, rugged and safe) method for the extraction and clean-up of UV photoinitiators in packaged foods was evaluated. Triple quadrupole working in H-SRM on Q1 mode was used for both quantitation and confirmation purposes and the most intense and selective transitions were chosen. Quality parameters of the developed QuEChERS LC-MS/MS method were established and applied for the analysis of photoinitiators in food packaged at ng kg-1 levels.
28 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.chroma.2010.11.054
Journal of Chromatography A, 2010, vol. 1218, num. 3, p. 459-466
http://dx.doi.org/10.1016/j.chroma.2010.11.054
(c) Elsevier B.V., 2010
info:eu-repo/semantics/openAccess
Envasament d'aliments
Espectrometria de masses
Cromatografia de líquids
Food packaging
Mass spectrometry
Liquid chromatography
Analysis of UV ink photoinitiators in packaged food by fast liquid chromatography at subambient temperature coupled to tandem mass spectrometry
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2613572017-05-23T04:49:37Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorGallart Ayala, Hèctor
authorNúñez Burcio, Oscar
authorMoyano Morcillo, Encarnación
authorGalcerán Huguet, M. Teresa
2016-05-03T08:15:51Z
2016-05-03T08:15:51Z
2010-04-26
2016-05-03T08:15:56Z
0173-0835
581180
http://hdl.handle.net/2445/98193
Conditions were established for the separation and analysis of Bisphenol A (BPA), Bisphenol F (BPF), and their diglycidyl ethers, by micellar electrokinetic capillary chromatography (MECC). Good resolution was obtained for all compounds, although in order to achieve the separation of ortho-ortho, ortho-para, and para-para isomers of Bisphenol F diglycidyl ether (BFDGE), BFDGE¿2H2O and BFDGE¿2HCl, it was necessary to use a 25 µm I.D. fused-silica capillary. To increase sensitivity, a field amplified sample injection (FASI)-MECC method was developed using 10 mM sodium dodecyl sulfate (SDS) solution as injection matrix and a 75 µm I.D. fused-silica capillary. Instrumental quality parameters such as limits of detection (0.999), and run-to-run and day-to-day precisions (relative standard deviations (RSD) values lower than 12.5%) were determined. Finally, the suitability of the FASI-MECC method for the analysis of BPA, BPF and their diglycidyl ethers in canned soft-drinks was evaluated. Quantitation was performed by matrix-matched calibration using a plastic-bottled isotonic drink as matrix. The results showed that FASI-MECC is an economic method for the screening and quantitation of these kinds of compounds in soft-drink beverages, with no loss of reproducibility, and effective at concentrations lower than the specific migration level (SML) values established by the European Union.
26 p.
application/pdf
eng
Wiley-VCH
Versió postprint del document publicat a: http://dx.doi.org/10.1002/elps.200900606
Electrophoresis, 2010, vol. 31, num. 9, p. 1550-1559
http://dx.doi.org/10.1002/elps.200900606
(c) Wiley-VCH, 2010
info:eu-repo/semantics/openAccess
Begudes carbòniques
Química dels aliments
Fenols
Cromatografia
Envasament d'aliments
Carbonated beverages
Food composition
Phenols
Chromatography
Food packaging
Field-amplified sample injection-micellar electrokinetic capillary chromatography for the analysis of bisphenol A, bisphenol F, and their diglycidyl ethers and derivatives in canned soft drinks
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2613582017-05-23T04:49:38Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorBernad Marcos, Josep Oriol
authorDamascelli, Anna
authorNúñez Burcio, Oscar
authorGalcerán Huguet, M. Teresa
2016-05-03T09:30:07Z
2016-05-03T09:30:07Z
2011-08-17
2016-05-03T09:30:13Z
0173-0835
596566
http://hdl.handle.net/2445/98197
Two in-line enrichment procedures (large volume sample stacking (LVSS) and field amplified sample injection (FASI)) have been evaluated for the capillary zone electrophoresis (CZE) analysis of haloacetic acids (HAAs) in drinking water. For LVSS, separation on normal polarity by using 20 mM acetic acid-ammonium acetate (pH 5.5) containing 20% acetonitrile as BGE was required. For FASI, the optimum conditions were 25 s hydrodynamic injection (3.5 kPa) of a water plug followed by 25 s electrokinetic injection (-10 kV) of the sample, and 200 mM formic acid-ammonium formate buffer at pH 3.0 as BGE. For both FASI and LVSS methods, linear calibration curves (r2>0.992), limit of detection (LOD) on standards prepared in Milli-Q water (49.1-200 µg/L for LVSS and 4.2-48 µg/L for FASI), and both run-to-run and day-to-day precisions (RSD values up to 15.8% for concentration) were established. Due to the higher sensitive enhancement (up to 310-fold) achieved with FASI-CZE this method was selected for the analysis of HAAs in drinking water. However, for an optimal FASI application sample salinity was removed by solid phase extraction (SPE) using Oasis WAX cartridges. With SPE-FASI-CZE, method detection limits in the range 0.05-0.8 µg/L were obtained, with recoveries, in general, higher than 90% (around 65% for monochloroacetic and monobromoacetic acids). The applicability of the SPE-FASI-CZE method was evaluated by analyzing a drinking tap water from Barcelona where seven HAAs were found at concentration levels between 3-13 µg/L.
23 p.
application/pdf
eng
Wiley-VCH
Versió postprint del document publicat a: http://dx.doi.org/10.1002/elps.201000676
Electrophoresis, 2011, vol. 32, num. 16, p. 2123-2130
http://dx.doi.org/10.1002/elps.201000676
(c) Wiley-VCH, 2011
info:eu-repo/semantics/openAccess
Acetats
Aigua potable
Electroforesi capil·lar
Contaminants
Acetates
Drinking water
Capillary electrophoresis
Pollutants
In-line preconcentration capillary zone electrophoresis for the analysis of haloacetic acids in water
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2855452017-05-23T04:49:39Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorSimón, Francesc Xavier
authorRudé i Payró, Elisabet
authorBerdalet i Andrés, Elisa
authorLlorens Llacuna, Joan
authorBaig, Sylvie
2013-04-08T06:28:13Z
2013-04-08T06:28:13Z
2013
2013-04-08T06:28:13Z
0045-6535
621579
http://hdl.handle.net/2445/34462
Biofilters degrade only a small fraction of the natural organic matter (NOM) contained in seawater which is the leading cause of biofouling in downstream processes. This work studies the effects of chemical additions on NOM biodegradation by biofilters. In this work, biofiltration of seawater with an empty bed contact time (EBCT) of 6 min and a hydraulic loading rate of 10 m h-1 reduces the biological oxygen demand (BOD7) by 8%, the dissolved organic carbon (DOC) by 6% and the UV absorbance at 254 nm (A254) by 7%. Different amounts of ammonium chloride are added to the seawater (up to twice the total dissolved nitrogen in untreated seawater) to study its possible effect on the removal of NOM by a pilot-scale biofilter. Seawater is amended with different amounts of easily biodegradable dissolved organic carbon (BDOC) supplied as sodium acetate (up to twice the DOC) for the same purpose. The results of this work reveal that the ammonium chloride additions do not significantly affect NOM removal and the sodium acetate is completely consumed by the biofiltration process. For both types of chemical additions, the BOD7, DOC and A254 in the outlet stream of the biofilter are similar to the values for the untreated control. These results indicate that this biofilter easily removes the BDOC from the seawater when the EBCT is not above 6 min. Furthermore, nitrogen does not limit the NOM biodegradation in seawater under these experimental conditions.
21 p.
application/pdf
eng
Elsevier Ltd
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.chemosphere.2013.02.056
Chemosphere, 2013, vol. 13, p. 1-21
http://dx.doi.org/10.1016/j.chemosphere.2013.02.056
(c) Elsevier Ltd, 2013
info:eu-repo/semantics/openAccess
Aigua de mar
Biodegradació
Depuració de l'aigua
Ecologia marina
Nitrogen
Seawater
Biodegradation
Water purification
Marine ecology
Nitrogen
Effects of inorganic nitrogen (NH4Cl) and biodegradable organic carbon (CH3COONa) additions on a pilot-scale seawater biofilter
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2613592017-05-23T04:49:39Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorGallart Ayala, Hèctor
authorNúñez Burcio, Oscar
authorMoyano Morcillo, Encarnación
authorGalcerán Huguet, M. Teresa
authorMartins, Cláudia P. B.
2016-05-03T09:56:29Z
2016-05-03T09:56:29Z
2011-09-13
2016-05-03T09:56:34Z
0951-4198
598809
http://hdl.handle.net/2445/98200
Benzophenone (BP) is one of the many contaminants reported as present in foodstuff due to its migration from food packaging materials. Liquid chromatography tandem mass spectrometry (LC-MS/MS) is acknowledged in the literature as the method of choice for this analysis. However, cases have been reported where the use of this methodology was not enough to unambiguously confirm the presence of a contaminant. In previous work performed by the authors, the unequivocal identification of BP in packaged foods was not possible even when monitoring two m/z transitions, since ion ratio errors higher than 20% were obtained. In order to overcome this analytical problem a fast, sensitive and selective liquid chromatography-high resolution-mass spectrometry (LC-HRMS) methodology has been developed and applied to the analysis of BP in packaged foods. A direct comparison between liquid chromatography high resolution mass spectrometry (LC-HRMS) and LC-MS/MS data indicated better selectivity when working with LC-HRMS at a resolving power of 50,000 FWHM than when monitoring two m/z transitions by LC-MS/MS. The resolving power used enabled the detection and identification of Harman as the compound impeding the confirmation of BP by LC-MS/MS. Similar quantitative results were obtained by an Orbitrap mass analyser (Exactive ¿) and a triple quadrupole mass analyser (TSQ Quantum Ultra AM ¿).
19 p.
application/pdf
eng
Wiley
Versió postprint del document publicat a: http://dx.doi.org/10.1002/rcm.5200
Rapid Communications in Mass Spectrometry, 2011, vol. 25, num. 20, p. 3161-3166
http://dx.doi.org/10.1002/rcm.5200
(c) Wiley, 2011
info:eu-repo/semantics/openAccess
Espectrometria de masses
Cromatografia
Envasament d'aliments
Química dels aliments
Mass spectrometry
Chromatography
Food packaging
Food composition
Preventing false negatives with high-resolution mass spectrometry: the benzophenone case
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2613602017-05-23T04:49:40Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorAstefanei, Alina
authorNúñez Burcio, Oscar
authorGalcerán Huguet, M. Teresa
2016-05-03T10:17:27Z
2016-05-03T10:17:27Z
2012-04-24
2016-05-03T10:17:33Z
1618-2642
605613
http://hdl.handle.net/2445/98201
As the interest in the use of fullerene compounds in biomedical and cosmetic applications increases, so too does the need to develop methods for their determination and quantitation in such complex matrices. In this work we studied the behavior of C60 and C70 fullerenes in non-aqueous capillary electrophoresis, as well as two C60 fullerene derivatives not previously reported by any electrophoretic method, N-methyl-fulleropyrrolidine (C60 pyrr) and (1,2-methanofullerene C60)-61-carboxylic acid (C60-COOH). . The separation was performed using fused-silica capillaries with an I.D. of 50 µm and tetraalkylammonium salts, namely tetra-n-decylammonium bromide (TDAB, 200 mM) and tetraethylammonium bromide (TEAB, 40 mM), in a solvent mixture containing 6% methanol and 10% acetic acid in acetonitrile:chlorobenzene (1:1 v/v) as the background electrolyte (BGE). Detection limits, based on a signal-to-noise ratio of 3:1, were calculated and values between 1 and 3.7 mg/L were obtained. Good run-to-run and day-to-day precisions on concentration were achieved with RDSs lower than 15%. For the first time, an electrophoretic technique (NACE) has been applied for the analysis of C60 fullerene in a commercial cosmetic cream. A standard addition method was used for quantitation and the result was compared with that obtained by analyzing the same cream by LC-MS.
21 p.
application/pdf
eng
Springer Verlag
Versió postprint del document publicat a: http://dx.doi.org/10.1007/s00216-012-6041-4
Analytical and Bioanalytical Chemistry, 2012
http://dx.doi.org/10.1007/s00216-012-6041-4
(c) Springer Verlag, 2012
info:eu-repo/semantics/openAccess
Ful·lerens
Electroforesi capil·lar
Fullerenes
Capillary electrophoresis
Non-aqueous capillary electrophoresis separation of fullerenes and C60 fullerene derivatives
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2613622017-05-23T04:49:42Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorNúñez Burcio, Oscar
authorGallart Ayala, Hèctor
authorMartins, Cláudia P. B.
authorMoyano Morcillo, Encarnación
authorGalcerán Huguet, M. Teresa
2016-05-03T11:11:31Z
2016-05-03T11:11:31Z
2012-05-17
2016-05-03T11:11:37Z
0003-2700
612803
http://hdl.handle.net/2445/98204
Atmospheric pressure photoionization (APPI) was evaluated for the analysis of fullerenes. An important response improvement was found when using toluene mediated APPI in negative mode if compared with other API sources (electrospray and atmospheric pressure chemical ionization). Fullerene APPI negative mass spectra were dominated by the isotopic cluster of the molecular ion, although isotopic patterns for M+1, M+2 and M+3 ions showed higher than expected relative abundances. These discrepancies are explained by the presence of two isobaric ions, one due to 13C and the other to the addition of hydrogen to a double bond of the fullerene structure. Triple quadrupole tandem mass spectrometry and ultra-high resolution mass spectrometry and accurate mass measurements were used to confirm these assignments. Additionally, cluster ions M+16 and M+32 were characterized following the same strategy. Ions due to the addition of oxygen and alkyl additions were attributed to the presence of methanol in the mobile phase. For the fast chromatographic separation of fullerenes (less than 3.5 min) a sub-2 µm C18 column and isocratic elution (toluene:methanol 45:55 v/v) was used. Highly selective-selected ion monitoring (H-SIM) mode (mass resolving power >12,500 FWHM) was proposed monitoring the two most intense isotope ions in the [M]-¿ cluster. Method limits of quantitation down to 10 pg L-1 for C60 and C70 fullerenes and between 0.75-5.0 ng L-1 for larger fullerenes were obtained. Finally, the UHPLC-APPI-MS method was used to analyze fullerenes in river and pond water samples.
26 p.
application/pdf
eng
American Chemical Society
Versió postprint del document publicat a: http://dx.doi.org/10.1021/ac300659h
Analytical Chemistry, 2012, vol. 84, num. 12, p. 5316-5326
http://dx.doi.org/10.1021/ac300659h
(c) American Chemical Society , 2012
info:eu-repo/semantics/openAccess
Ful·lerens
Espectrometria de masses
Pressió atmosfèrica
Materials nanoestructurats
Fullerenes
Mass spectrometry
Atmospheric pressure
Nanostructured materials
Atmospheric pressure photoionization mass spectrometry of fullerenes
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2613982017-05-23T04:49:45Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorNúñez Burcio, Oscar
authorGallart Ayala, Hèctor
authorMartins, Cláudia P. B.
authorLucci, Paolo
2016-05-04T10:40:10Z
2016-05-04T10:40:10Z
2012-11-07
2016-05-04T10:40:15Z
0021-9673
605612
http://hdl.handle.net/2445/98259
There is an increasing need for applications in food and environmental areas able to cope with a large number of analytes in very complex matrices. The new analytical procedures demand sensitivity, robustness and high resolution within an acceptable analysis time. The purpose of this review is to describe new trends based on fast liquid chromatography applied to the food and environmental analysis. It includes different column technologies, such as monolithic, sub-2 m, porous shell, as well as different stationary phases such as reversed phase (C8 and C18), hydrophilic interaction liquid chromatography (HILIC) and fluorinated columns. Additionally, recent sample extraction and clean-up methodologies applied to reduce sample manipulation and total analysis time in food and environmental analysis - QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe), on line solid phase extraction coupled to ultrahigh pressure liquid chromatography (on line SPE-UHPLC), turbulent flow chromatography (TFC) and molecularly imprinted polymers (MIPs), were also addressed. The advantages and drawbacks of these methodologies applied to the fast and sensitive analyses of food and environmental samples are going to be discussed.
26 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.chroma.2011.10.091
Journal of Chromatography A, 2012, vol. 1228, p. 298-323
http://dx.doi.org/10.1016/j.chroma.2011.10.091
(c) Elsevier B.V., 2012
info:eu-repo/semantics/openAccess
Cromatografia de líquids
Química dels aliments
Contaminació de l'aigua
Liquid chromatography
Food composition
Water pollution
New trends in fast liquid chromatography for food and environmental analysis
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2613992017-05-23T04:49:46Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorNúñez Burcio, Oscar
authorGallart Ayala, Hèctor
authorFerrer, Imma
authorMoyano Morcillo, Encarnación
authorGalcerán Huguet, M. Teresa
2016-05-04T10:52:49Z
2016-05-04T10:52:49Z
2012-06-16
2016-05-04T10:52:54Z
0021-9673
580799
http://hdl.handle.net/2445/98263
Analytical strategies for screening, quantitation and confirmation of a group of 100 pesticides in fruit and vegetable samples by LC-MS and LC-MS/MS were developed. The pesticides studied belong to different chemical families of herbicides, insecticides and fungicides. A selection of some degradation products was also included. Chromatographic separation was performed using a Zorbax Eclipse XDB-C8 column (150 mm × 4.6 mm and 5 µm particle size), and gradient elution with acetonitrile-water (both with 0.1% formic acid) as mobile phase. LC-MS/MS using highly-selective selected reaction monitoring (H-SRM) acquisition mode monitoring two transitions for each compound showed to be the most sensitive methodology. Quantitation was carried out using matrix-matched standard calibration and good linearity of response was demonstrated (r > 0.998). Limits of detection (by acquiring two transitions and with the ion-ratio requirements) ranged between 0.01 and 20 µg/kg were obtained. So, in general, the sensitivity achieved meets the maximum residue levels (MRLs) established by the European Union regulation for food monitoring programs. Pesticide confirmation was carried out following European Union guidelines. In order to prevent false-positives, further confirmatory strategies were proposed. LC-MS in highly-selective selected ion monitoring (H-SIM) mode with accurate mass measurement was used to obtain an orthogonal criterion (exact mass) for confirmation. Accurate mass measurements were always bellow 0.9 mDa for almost all pesticides studied (similar to those described with TOF instruments). A user reversed energy ramp (RER) product ion scan spectra library was generated by means of a data dependent analysis for routine library searching of pesticides. The combination of LC-MS/MS in H-SRM mode and the generation of the RER product ion scan spectra and library search were then used to achieve further confirmation on pesticide analysis. The LC-MS and LC-MS/MS strategies developed were successfully applied for the analysis and confirmation of pesticides in different types of fruit and vegetables samples, and examples of the screening, quantitation and confirmation of pesticides in these samples are shown in this work.
17 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.chroma.2012.06.028
Journal of Chromatography A, 2012, vol. 1249, p. 164-180
http://dx.doi.org/10.1016/j.chroma.2012.06.028
(c) Elsevier B.V., 2012
info:eu-repo/semantics/openAccess
Plaguicides
Química dels aliments
Cromatografia de líquids
Pesticides
Food composition
Liquid chromatography
Strategies for the multi-residue analysis of 100 pesticides by liquid chromatography-triple quadrupole mass spectrometry
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2614002017-05-23T04:49:47Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorGallart Ayala, Hèctor
authorNúñez Burcio, Oscar
authorLucci, Paolo
2016-05-04T11:20:56Z
2016-05-04T11:20:56Z
2012
2016-05-04T11:21:02Z
0165-9936
614410
http://hdl.handle.net/2445/98270
The supply of safe and high-quality foodstuffs relies on the efficient protection of food from deterioration. However, all food-packaging materials can release small amounts of their chemical constituents when they touch food, and any substance that migrates from the packaging into the food is of concern if it could pose health problems to the consumer. The purpose of this review is to describe recent advances in the liquid chromatography-mass spectrometry (LC-MS) analysis of food-packaging contaminants since 2009, focusing on some relevant families of compounds (e.g., bisphenol A, bisphenol A diglycidyl ethers and related compounds, UV-ink photoinitiators, perfluorinated compounds, and phthalates).
26 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.trac.2012.09.017
Trac-Trends in Analytical Chemistry, 2012, vol. 42, p. 99-124
http://dx.doi.org/10.1016/j.trac.2012.09.017
(c) Elsevier B.V., 2012
info:eu-repo/semantics/openAccess
Envasament d'aliments
Contaminació dels aliments
Cromatografia de líquids
Espectrometria de masses
Food packaging
Food contamination
Liquid chromatography
Mass spectrometry
Recent advances in LC-MS analysis of food packaging contaminants
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2614012017-05-23T04:49:49Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorAstefanei, Alina
authorNúñez Burcio, Oscar
authorGalcerán Huguet, M. Teresa
authorKok, Wim Th
authorSchoenmakers, P.J.
2016-05-04T11:50:13Z
2016-08-20T22:01:17Z
2015-08-20
2016-05-04T11:50:18Z
1618-2642
653927
http://hdl.handle.net/2445/98275
In this work the electrophoretic behaviour of hydrophobic fullerenes (C60, C70 and C60-pyrr) and water soluble fullerenes (C60(OH)24, C120(OH)30, C60-pyrr tris acid and C60CHCOOH) in micellar electrokinetic capillary chromatography (MECC) was evaluated. The aggregation behavior of the water soluble compounds in MECC at different buffer and SDS concentrations and pH values of the background electrolyte (BGE) was studied by monitoring the changes observed in the electrophoretic pattern of the peaks. Broad and distorted peaks that can be attributed to fullerene aggregation were obtained in MECC which became narrower and more symmetric by working at low buffer and SDS concentrations (below the critical micelle concentration, capillary zone electrophoresis (CZE) conditions). For the characterization of the suspected aggregates formed (size and shape), asymmetrical flow field-flow fractionation (AF4) and transmission electron microscopy (TEM) were used. The results showed that the increase in the buffer concentration promoted the aggregation of the particles while the presence of SDS micelles revealed multiple peaks corresponding to particles of different aggregation degree. Furthermore, MECC has been applied for the first time for the analysis of C60 in two different cosmetic products (i.e., anti-aging serum and facial mask).
11 p.
application/pdf
eng
Springer Verlag
Versió postprint del document publicat a: http://dx.doi.org/10.1007/s00216-015-8976-8
Analytical and Bioanalytical Chemistry, 2015, vol. 407, num. 26, p. 8035-8045
http://dx.doi.org/10.1007/s00216-015-8976-8
(c) Springer Verlag, 2015
info:eu-repo/semantics/openAccess
Ful·lerens
Electroforesi capil·lar
Fullerenes
Capillary electrophoresis
Aggregation behaviour of fullerenes in aqueous solutions: a capillary electrophoresis and asymmetric flow-field flow fractionation study
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2614022017-05-23T04:49:50Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorMartínez-Villalba, Anna
authorNúñez Burcio, Oscar
authorMoyano Morcillo, Encarnación
authorGalcerán Huguet, M. Teresa
2016-05-04T12:19:09Z
2016-05-04T12:19:09Z
2013-03-13
2016-05-04T12:19:14Z
0173-0835
615670
http://hdl.handle.net/2445/98278
Veterinary medicines are widely administered to farm animals since they keep animals healthy at overcrowded conditions. Nevertheless the continuous administration of medicines to farm animals can frequently lead to the presence of residues of veterinary drugs in consumption products. Amprolium is a quaternary ammonium compound used in the treatment of coccidiosis. In this paper a method based on capillary zone electrophoresis (CZE) to analyze residues of amprolium in eggs was developed and validated for the first time. Parameters such as electrolyte type, concentration and pH were optimized. In order to improve sensitivity, field amplified sample injection (FASI) was used for in-line preconcentration after a quick and simple sample treatment based on SPE (Envi-Carb). During method validation studies using egg samples a matrix interference was found at the migration time of amprolium. This compound was identified as thiamine and confirmed by MSn experiments using capillary electrophoresis coupled to mass spectrometry (CE-MS) with an ion-trap mass analyzer. CZE conditions were re-optimized to separate thiamine from amprolium allowing the quantification of amprolium in eggs at concentrations down to 75 µg Kg-1, which are far below the MRL legislated values.
7 p.
application/pdf
eng
Wiley-VCH
Versió postprint del document publicat a: http://dx.doi.org/10.1002/elps.201200579
Electrophoresis, 2013, vol. 34, num. 6, p. 870-876
http://dx.doi.org/10.1002/elps.201200579
(c) Wiley-VCH, 2013
info:eu-repo/semantics/openAccess
Química dels aliments
Electroforesi capil·lar
Food composition
Capillary electrophoresis
Field amplified sample injection-capillary zone electrophoresis for the analysis of amprolium in eggs
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2615702017-05-23T04:49:52Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorMartins, Isabel
authorGarcia, Helga
authorVarela, Adélia
authorNúñez Burcio, Oscar
authorPlanchon, Sébastien
authorGalcerán Huguet, M. Teresa
authorRenaut, Jenny
authorRebelo, Luís P. N.
authorPereira, Cristina Silvia
2016-05-06T11:28:00Z
2016-05-06T11:28:00Z
2013-12-04
2016-05-06T11:28:05Z
1874-3919
630497
http://hdl.handle.net/2445/98390
Cork, the outer bark of Quercus suber, shows a unique compositional structure, a set of remarkable properties, including high recalcitrance. Cork colonisation by Ascomycota remains largely overlooked. Herein, Aspergillus nidulans secretome on cork was analysed (2DE). Proteomic data were further complemented by microscopic (SEM) and spectroscopic (ATRFTIR) evaluation of the colonised substrate and by targeted analysis of lignin degradation compounds (UPLC-HRMS). Data showed that the fungus formed an intricate network of hyphae around the cork cell walls, which enabled polysaccharides and lignin superficial degradation, but probably not of suberin. The degradation of polysaccharides was suggested by the identification of few polysaccharide degrading enzymes (β-glucosidases and endo-1,5--L-arabinosidase). Lignin degradation, which likely evolved throughout a Fenton-like mechanism relying on the activity of alcohol oxidases, was supported by the identification of small aromatic compounds (e.g. cinnamic acid and veratrylaldehyde) and of several putative high molecular weight lignin degradation products. In addition, cork recalcitrance was corroborated by the identification of several protein species which are associated with autolysis. Finally, stringent comparative proteomics revealed that A. nidulans colonisation of cork and wood share a common set of enzymatic mechanisms. However the higher polysaccharide accessibility in cork might explain the increase of β-glucosidase in cork secretome
14 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.jprot.2013.11.023
Journal of Proteomics, 2013, vol. 98, p. 175-188
http://dx.doi.org/10.1016/j.jprot.2013.11.023
(c) Elsevier B.V., 2013
info:eu-repo/semantics/openAccess
Suro
Roures
Fongs
Cork
Oak
Fungi
Investigating Aspergillus nidulans secretome during colonisation of cork cell walls
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2615712017-05-23T04:49:53Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorRodríguez, Juanita C.
authorGómez, Daniela
authorPacetti, Deborah
authorNúñez Burcio, Oscar
authorGagliardi, Riccardo
authorFrega, Natale G.
authorOjeda, Myriam L.
authorLoizzo, Monica R.
authorTundis, Rosa
authorLucci, Paolo
2016-05-06T11:40:23Z
2017-01-11T23:01:11Z
2016-01-11
2016-05-06T11:40:28Z
0021-8561
656276
http://hdl.handle.net/2445/98392
In the present study, we assessed for the first time the changes in the antioxidant capacity, total phenolic content, and polyphenolic composition of interspecific hybrid palm oil extracted from Elaeis oleifera x Elaeis guineensis (O×G, Coari × La Mé cultivar) during the fruit ripening process 18, 20, 22, and 24 weeks after anthesis. A progressive decrease (p<0.05) of phenolic content occurred during fruit development together with marked changes in polyphenol profiles. Significant negative correlations were established between antioxidant activity measured by TEAC (R = -0.954, p<0.05) and ORAC (R = -0.745, p<0.05) and fruits ripening stage while positive correlation between total phenolic content was found using either the TEAC assay or the ORAC assay. Highest DPPH radicals scavenging activity was also obtained with oils extracted at 18 WAA. These results highlight that O×G fruits of early ripeness represent a better source of phenolic compounds and may provide extracts with higher antioxidant activities when hybrid palm oil is aimed to be used as functional ingredient for the development of food or food products with antioxidant properties.
8 p.
application/pdf
eng
American Chemical Society, Books and Journals Division]
Versió postprint del document publicat a: http://dx.doi.org/10.1021/acs.jafc.5b04990
Journal of Agricultural and Food Chemistry, 2016, vol. 64, num. 4, p. 852-859
http://dx.doi.org/10.1021/acs.jafc.5b04990
(c) American Chemical Society, Books and Journals Division], 2016
info:eu-repo/semantics/openAccess
Polifenols
Olis vegetals
Oli de palma
Polyphenols
Vegetable oils
Palm oil
Effects of the fruit ripening stage on antioxidant capacity, total phenolics, and polyphenolic composition of crude palm oil from interspecific hybrid Elaeis oleifera × Elaeis guineensis
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2615982017-05-23T04:49:54Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorLucci, Paolo
authorNúñez Burcio, Oscar
authorGalcerán Huguet, M. Teresa
2016-05-09T07:22:46Z
2016-05-09T07:22:46Z
2011-02-13
2016-05-09T07:22:51Z
0021-9673
596565
http://hdl.handle.net/2445/98420
A method is proposed for the clean-up and preconcentration of natural and synthetic estrogens from aqueous samples employing molecularly imprinted polymer (MIP) as selective sorbent for solid-phase extraction (SPE). The selectivity of the MIP was checked toward several selected natural and synthetic estrogens such as estrone (E1), 17β-estradiol (β-E2), 17α-estradiol (α-E2), estriol (E3), 17α-ethinylestradiol (EE2), dienestrol (DIES) and diethylstilbestrol (DES). Ultrahigh pressure liquid chromatography (UHPLC) coupled to a TSQ triple quadrupole mass spectrometry (QqQ) was used for analysis of target analytes. The chromatographic separation of the selected compounds was performed in less than 2 min under isocratic conditions. The method was applied to the analysis of estrogens in spiked river and tap water samples. High recoveries (>82%) for estrone, 17β-estradiol, 17α-estradiol, estriol and 17α-ethinylestradiol were obtained. Lower but still satisfactory recoveries (>48%) were achieved for dienestrol and diethylstilbestrol. The method was validated and found to be linear in the range 50-500 ng L-1 with correlation coefficients (R2) greater than 0.995 and repeatability relative standard deviation (RSD) below 8% in all cases. For analysis of 100-ml sample, the method detection limits (LOD) ranged from 4.5 to 9.8 ng L-1 and the limit of quantitation (LOQ) from 14.9 to 32.6 ng L-1. To demonstrate the potential of the MIP obtained, a comparison with commercially available C18 SPE was performed. Molecularly imprinted SPE showed higher recoveries than commercially available C18 SPE for most of the compounds. These results showed the suitability of the MIP-SPE method for the selective extraction of a class of structurally related compounds such as natural and synthetic estrogens.
6 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.chroma.2011.02.007
Journal of Chromatography A, 2011, vol. 1218, num. 30, p. 4828-4833
http://dx.doi.org/10.1016/j.chroma.2011.02.007
(c) Elsevier B.V., 2011
info:eu-repo/semantics/openAccess
Estrògens
Cromatografia de líquids d'alta resolució
Espectrometria de masses
Estrogen
High performance liquid chromatography
Mass spectrometry
Solid-phase extraction using molecularly imprinted polymer for selective extraction of natural and syntetic estrogens from aqueous samples
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2616002017-05-23T04:49:56Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorTeixidó, Erika
authorNúñez Burcio, Oscar
authorSantos Vicente, Francisco Javier
authorGalcerán Huguet, M. Teresa
2016-05-09T09:44:06Z
2016-05-09T09:44:06Z
2010-12-10
2016-05-09T09:44:11Z
0308-8146
582867
http://hdl.handle.net/2445/98432
Micellar electrokinetic chromatography (MEKC) has been applied for the determination of 5-hydroxymethylfurfural in several foodstuffs. A 75 mM phosphate buffer solution at pH 8.0 containing 100 mM sodium dodecylsulfate was used as background electrolyte (BGE), and the separation was performed by applying +25 kV in a 50 µm I.D. uncoated fused-silica capillary. Good linearity over the range 2.5-250 mg kg-1 (r2 ≥ 0.999) and run-to-run and day-to-day precisions at low and medium concentration levels were obtained. Sample limit of detection (0.7 mg kg-1) and limit of quantification (2.5 mg kg-1) were established by preparing the standards in blank matrix. The procedure was validated by comparing the results with those obtained with liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Levels of HMF in 45 different foodstuffs such as breakfast cereals, toasts, honey, orange juice, apple juice, jam, coffee, chocolate and biscuits were determined.
7 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.foodchem.2010.12.016
Food Chemistry, 2010, vol. 126, num. 4, p. 1902-1908
http://dx.doi.org/10.1016/j.foodchem.2010.12.016
(c) Elsevier B.V., 2010
info:eu-repo/semantics/openAccess
Química dels aliments
Cromatografia
Food composition
Chromatography
5-Hydroxymethylfurfural content in foodstuffs determined by micellar electrokinetic chromatography
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2616012017-05-23T04:49:57Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorNúñez Burcio, Oscar
authorGallart Ayala, Hèctor
authorMartins, Cláudia P. B.
authorLucci, Paolo
authorBusquets, Rosa
2016-05-09T10:06:54Z
2016-05-09T10:06:54Z
2013-01-10
2016-05-09T10:07:00Z
1570-0232
615797
http://hdl.handle.net/2445/98436
There is an increasing need of new bio-analytical methodologies with enough sensitivity, robustness and resolution to cope with the analysis of a large number of analytes in complex matrices in short analysis time. For this purpose, all steps included in any bio-analytical method (sampling, extraction, clean-up, chromatographic analysis and detection) must be taken into account to achieve good and reliable results with cost-effective methodologies. The purpose of this review is to describe the state-of-the-art of the most employed technologies in the period 2009-2012 to achieve fast analysis with liquid chromatography coupled to mass spectrometry (LC-MS) methodologies for bio-analytical applications. Current trends in fast liquid chromatography involve the use of several column technologies and this review will focus on the two most frequently applied: sub-2 µm particle size packed columns to achieve ultra high pressure liquid chromatography (UHPLC) separations and porous-shell particle packed columns to attain high efficiency separations with reduced column back-pressures. Additionally, recent automated sample extraction and clean-up methodologies to reduce sample manipulation, variability and total analysis time in bio-analytical applications such as on-line solid phase extraction coupled to HPLC or UHPLC methods, or the use of other approaches such as molecularly imprinted polymers, restricted access materials, and turbulent flow chromatography will also be addressed. The use of mass spectrometry and high or even ultra-high resolution mass spectrometry to reduce sample manipulation and to solve ion suppression or ion enhancement and matrix effects will also be presented. The advantages and drawbacks of all these methodologies for fast and sensitive analysis of biological samples are going to be discussed by means of relevant applications.
19 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.jchromb.2012.12.031
Journal Of Chromatography B-Analytical Technologies In The Biomedical And Life Sciences, 2013, vol. 927, p. 3-21
http://dx.doi.org/10.1016/j.jchromb.2012.12.031
(c) Elsevier B.V., 2013
info:eu-repo/semantics/openAccess
Cromatografia
Marcadors bioquímics
Espectrometria de masses
Chromatography
Biochemical markers
Mass spectrometry
State-of-the-art in fast liquid chromatography-mass spectrometry for bioanalytical applications
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2616022017-05-23T04:49:58Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorLucci, Paolo
authorNúñez Burcio, Oscar
2016-05-09T11:44:14Z
2016-05-09T11:44:14Z
2014-07-18
2016-05-09T11:44:19Z
1615-9306
642740
http://hdl.handle.net/2445/98441
Public concern about pesticides in food and water has increased dramatically in the last two decades. In order to guarantee consumers' health and safety, analytical methods that could provide fast and reliable answers without compromising accuracy and precision are required. Sample treatment is probably the most tedious and time-consuming step in many analytical procedures and, despite the significant advances in chromatographic separations and mass spectrometry techniques, sample treatment is still one of the most important parts of the analytical process for achieving good analytical results. Therefore, over the last years, considerable efforts have been made to simplify the stage and to develop fast, accurate and robust methods which allow the determination of a wide range of pesticides without compromising the integrity of the extraction process. This review article intends to give a short overview of recently developed on-line solid-phase extraction, pre-concentration and clean-up procedures for the determination of pesticides in complex matrices by liquid chromatography-mass spectrometry techniques.
11 p.
application/pdf
eng
Wiley-VCH
Versió postprint del document publicat a: http://dx.doi.org/10.1002/jssc.201400331
Journal of Separation Science, 2014, vol. 37, p. 2929-2939
http://dx.doi.org/10.1002/jssc.201400331
(c) Wiley-VCH, 2014
info:eu-repo/semantics/openAccess
Plaguicides
Espectrometria de masses
Química dels aliments
Cromatografia de líquids
Anàlisi de l'aigua
Pesticides
Mass spectrometry
Food composition
Liquid chromatography
Water analysis
On-line solid-phase extraction for liquid chromatography-mass spectrometry analysis of pesticides
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2621252017-05-23T04:49:59Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorHarutyunyan, Shushan
authorKumar, Mohit
authorSedivy, Arthur
authorSubirats i Vila, Xavier
authorKowalski, Heinrich
authorKöhler, Gottfried
authorBlaas, Dieter
2016-05-24T07:44:03Z
2016-05-24T07:44:03Z
2013-04-01
2016-05-18T16:50:16Z
1553-7374
631108
http://hdl.handle.net/2445/98786
Upon infection, many RNA viruses reorganize their capsid for release of the genome into the host cell cytosol for replication. Often, this process is triggered by receptor binding and/or by the acidic environment in endosomes. In the genus Enterovirus, which includes more than 150 human rhinovirus (HRV) serotypes causing the common cold, there is persuasive evidence that the viral RNA exits single-stranded through channels formed in the protein shell. We have determined the time-dependent emergence of the RNA ends from HRV2 on incubation of virions at 56°C using hybridization with specific oligonucleotides and detection by fluorescence correlation spectroscopy. We report that psoralen UV crosslinking prevents complete RNA release, allowing for identification of the sequences remaining inside the capsid. We also present the structure of uncoating intermediates in which parts of the RNA are condensed and take the form of a rod that is directed roughly towards a two-fold icosahedral axis, the presumed RNA exit point. Taken together, in contrast to schemes frequently depicted in textbooks and reviews, our findings demonstrate that exit of the RNA starts from the 3′-end. This suggests that packaging also occurs in an ordered manner resulting in the 3′-poly-(A) tail becoming located close to a position of pore formation during conversion of the virion into a subviral particle. This directional genome release may be common to many icosahedral non-enveloped single-stranded RNA viruses
14 p.
application/pdf
eng
Public Library of Science (PLoS)
Reproducció del document publicat a: http://dx.doi.org/10.1371/journal.ppat.1003270
PLoS Pathogens, 2013, vol. 9, num. 4, p. e1003270
http://dx.doi.org/10.1371/journal.ppat.1003270
cc-by (c) Harutyunyan, Shushan et al., 2013
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by/3.0/es">http://creativecommons.org/licenses/by/3.0/es</a>
Reovirus
RNA
Hibridació
Reoviruses
RNA
Hybridization
Viral uncoating is directional: exit of the genomic RNA in a common cold virus starts with the poly-(A) tail at the 3′-end
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2622312017-05-23T04:50:01Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorPurrà, Miquel
authorCinca, Roser
authorLegaz, Jessica
authorNúñez Burcio, Oscar
2016-05-30T10:45:48Z
2016-05-30T10:45:48Z
2014-08-22
2016-05-30T10:45:53Z
1618-2642
642831
http://hdl.handle.net/2445/99019
A field amplified sample injection-capillary zone electrophoresis (FASI-CZE) method for the analysis of benzophenone (BP) UV-filters in environmental water samples was developed, allowing the separation of all compounds in less than 8 minutes. A 9- to 25-fold sensitive enhancement was obtained with FASI-CZE, achieving limits of detection down to 21-59 µg/L for most of the analyzed BPs, with acceptable run-to-run and day-to-day precisions (relative standard deviations lower than 17%). In order to remove water sample salinity and to enhance FASI sensitivity, an off-line solid-phase extraction (SPE) procedure using a Strata X polymeric reversed-phase sorbent was proposed, obtaining recoveries up to 72-90% for most of benzophenones. With the combination of off-line SPE and FASI-CZE, limits of detection in the range 0.06-0.6 µg/L in a river water matrix, representing a 2400- to 6500-fold enhancement, were obtained. Method performance was evaluated by quantifying a blank river water sample spiked at 1 µg/L. For a 95% confidence level, no statistical differences were observed between found concentrations and spiked concentrations (probability at the confidence level, p value, of 0.60), showing that the proposed off-line SPE-FASI-CZE method is suitable for the analysis of benzophenone UV-filters in environmental water samples at low µg/L levels. The method was successfully applied to the analysis of BPs in river water samples collected before and after industrialized and urban areas, and in some drinking water samples.
14 p.
application/pdf
eng
Springer Verlag
Versió postprint del document publicat a: http://dx.doi.org/10.1007/s00216-014-8086-z
Analytical and Bioanalytical Chemistry, 2014, vol. 406, num. 25, p. 6189-6202
http://dx.doi.org/10.1007/s00216-014-8086-z
(c) Springer Verlag, 2014
info:eu-repo/semantics/openAccess
Anàlisi de l'aigua
Electroforesi capil·lar
Water analysis
Capillary electrophoresis
Solid-phase extraction and field-amplified sample injection-capillary zone electrophoresis for the analysis of benzophenone UV-filters in environmental water samples
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2622322017-05-23T04:50:02Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorAstefanei, Alina
authorNúñez Burcio, Oscar
authorGalcerán Huguet, M. Teresa
2016-05-30T12:34:12Z
2016-05-30T12:34:12Z
2014-09-02
2016-05-30T12:34:17Z
0021-9673
642832
http://hdl.handle.net/2445/99043
In this work, a method is proposed for the simultaneous analysis of several pristine fullerenes (C60, C70, C76, C78, and C84) and three C60-fullerene derivatives (N-methyl fulleropyrrolidine, [6,6]-Phenyl C61 butyric acid methyl ester and [6,6]-Phenyl C61 butyric acid buthyl ester) in environmental samples. The method involves the use of ultrahigh performance liquid chromatography coupled to atmospheric pressure photoionization mass spectrometry (UHPLC-APPI-MS) and allowed the chromatographic separation in less than 4.5 minutes. The product ions from tandem mass spectrometry studies of fullerene derivatives, were characterized and the most abundant one (m/z 720), corresponding to [C60]-¿, was selected for quantitation. Selected reaction monitoring (SRM at 0.7 m/z FWHM) by acquiring two transitions using both isotopic cluster ions [M]-¿ and [M+1]-¿ as precursor ions was proposed for quantitation and confirmation purposes. For pristine fullerenes, highly-selective selected ion monitoring (H-SIM) acquisition mode by monitoring the isotopic cluster ions [M]-¿ and [M+1]-¿ was used. Pressurized solvent extraction conditions were optimized in order to improve recoveries of the studied fullerene compounds from sediment samples. Values up to 87-92% for C60-fullerene derivatives and lower but still acceptable, 70-80%, for pristine fullerenes were obtained. Method limits of quantitation (MLOQs) ranging from 1.5 pg L-1to 5.5 ng L-1 in water samples and from 0.1 ng Kg-1 to 523 ng Kg-1 in sediments were obtained with good precision (relative standard deviations always lower than 13%). The applicability of the developed method was evaluated by analyzing several environmental samples such as sediments and pond water and the detected levels for C60-fullerene derivatives were of 0.1-2.7 ng Kg-1and 1.5-8.5 pg L-1, respectively. C60 and C70 were the only pristine fullerenes detected in the analyzed samples (0.1-7.2 ng Kg-1 in sediments and 9-330 pg L-1 in water pond samples).
11 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.chroma.2014.08.089
Journal of Chromatography A, 2014, vol. 1365, p. 61-71
http://dx.doi.org/10.1016/j.chroma.2014.08.089
(c) Elsevier B.V., 2014
info:eu-repo/semantics/openAccess
Ful·lerens
Espectrometria de masses
Cromatografia de líquids d'alta resolució
Mostreig mediambiental
Fullerenes
Mass spectrometry
High performance liquid chromatography
Environmental sampling
Analysis of C60-fullerene fullerene derivatives and pristine fullerenes in environmental samples by ultrahigh performance liquid chromatography-atmospheric pressure photoionization-mass spectrometry
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2622722017-05-23T04:50:03Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorCadenas, Madelin
authorBringue Tomás, Roger
authorFité Piquer, Carles
authorIborra Urios, Montserrat
authorRamírez, Eliana
authorCunill García, Fidel
2016-05-31T08:11:06Z
2016-05-31T08:11:06Z
2014-08-11
2016-05-31T08:11:12Z
0926-860X
642892
http://hdl.handle.net/2445/99064
The macroreticular acidic ion-exchange resins Amberlyst 35, Amberlyst 46 and Purolite CT 275 were investigated as catalysts for the alkylation of toluene with 1-hexene and simultaneous dimerization and isomerization of the olefin at 373 K. After six hours of reaction, 1-hexene conversion was complete. At low toluene concentration double-bound isomerization of 1-hexene was the main reaction. As toluene concentration increased, double-bond isomerization decreased and toluene alkylation and olefin dimerization reactions increased. By using Purolite CT 275 resin and for an almost equimolar toluene to 1-hexene ratio, the selectivity to dimers was 22%, that of mono- and di-alkylated compounds were 42% and 3.5%, respectively, while that of double-bound isomerization was 32.5%. These reactions catalyzed by macroreticular ion-exchange resins of high acid capacity and degree of crosslinking can be useful to boost naphtha streams in the refining industry by reducing volatile compounds and aromatics of low boiling point.
6 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.apcata.2014.07.044
Applied Catalysis A-General, 2014, vol. 485, p. 143-148
http://dx.doi.org/10.1016/j.apcata.2014.07.044
(c) Elsevier B.V., 2014
info:eu-repo/semantics/openAccess
Resines de bescanvi iònic
Catàlisi
Ion exchange resins
Catalysis
Alkylation of toluene with 1-hexene over macroreticular ion-exchange resins
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2622732017-05-23T04:50:12Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorBringue Tomás, Roger
authorRamírez Rangel, Eliana
authorIborra Urios, Montserrat
authorTejero Salvador, Xavier
authorCunill García, Fidel
2016-05-31T09:57:02Z
2016-05-31T09:57:02Z
2014-02-22
2016-05-31T09:57:07Z
1385-8947
635115
http://hdl.handle.net/2445/99068
The kinetics of the liquid-phase etherification of 1-hexanol to di-n-ethyl ether and water on the ion-exchange resin Amberlyst 70 in the temperature range 423-463 K is studied. The strong inhibition effect of water is considered following two approaches. First, a model stemming from a Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism was used, wherein the inhibitor effect of water was explained by the competitive adsorption of water and hexanol. Secondly, a modified Eley-Rideal (ER) model that includes an inhibition factor, in which a Freundlich-like function is used to explain the inhibitor effect of water by blocking the access of hexanol to the active centers. Both models fitted data quite well, although the best fitting results were obtained with the modified ER model. The activation energy was 125 ± 3 kJ/mol for the LHHW model and 121 ± 3 kJ/mol for the modified ER one
8 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.cej.2014.02.042
Chemical Engineering Journal, 2014, vol. 246, p. 71-78
http://dx.doi.org/10.1016/j.cej.2014.02.042
(c) Elsevier B.V., 2014
info:eu-repo/semantics/openAccess
Resines de bescanvi iònic
Èters
Cinètica enzimàtica
Alcohols
Catàlisi
Ion exchange resins
Ethers
Enzyme kinetics
Alcohols
Catalysis
Kinetics of 1-hexanol etherification on Amberlyst 70
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2622742017-05-23T04:50:13Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorPérez-Maciá, María Ángeles
authorBringue Tomás, Roger
authorIborra Urios, Montserrat
authorTejero Salvador, Xavier
authorCunill García, Fidel
2016-05-31T10:16:47Z
2015-06-11
2016-05-31T10:16:52Z
info:eu-repo/date/embargoEnd/2017-06-11
0263-8762
654737
http://hdl.handle.net/2445/99072
The thermodynamic equilibrium of the bimolecular dehydration of 1-butanol to di-n-butyl ether (DNBE) and water in the liquid phase was studied. Equilibrium experiments were performed at 4 MPa and in the temperature range of 413-463 K over the ion exchange resin Amberlyst-70. The thermodynamic equilibrium for the side reactions (dehydration to 1-butene, olefins isomerization, olefins hydration and branched ether formation) was also studied. The equilibrium constant for the dehydration reaction of 1-butanol to di-n-butyl ether and water was found to be independent on the operating temperature, within the limits of the experimental error ( 5.2%). The experimental equilibrium constants at 413-463 K allows to estimate the standard enthalpy change of reaction (ΔrH0(l) = -0.3 ± 2.9 kJ¿mol-1) and the standard entropy change of reaction (ΔrS0(l) = 26.8 ± 6.7 J¿mol-1¿K-1). From these values the standard formation enthalpy (ΔfH0DNBE,(l)) and the molar entropy of DNBE (S0DNBE,(l)) at 298.15 K were computed to be -370.5 ± 10.9 kJ¿mol-1 and 408.3 ± 6.8 J¿mol-1¿K-1 respectively
10 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.cherd.2015.06.007
Chemical Engineering Research & Design, 2015, vol. 102, p. 186-195
http://dx.doi.org/10.1016/j.cherd.2015.06.007
cc-by-nc-nd (c) Elsevier B.V., 2015
info:eu-repo/semantics/embargoedAccess
<a href="http://creativecommons.org/licenses/by-nc-nd/3.0/es">http://creativecommons.org/licenses/by-nc-nd/3.0/es</a>
Èters
Alcohol butílic
Resines de bescanvi iònic
Ethers
Butanol
Ion exchange resins
Thermodynamic equilibrium for the dehydration of 1-butanol to di-n-butyl ether
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2622752017-05-23T04:50:13Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorPérez-Maciá, María Ángeles
authorBringue Tomás, Roger
authorIborra Urios, Montserrat
authorTejero Salvador, Xavier
authorCunill García, Fidel
2016-05-31T11:40:26Z
2016-05-31T11:40:26Z
2014-05-24
2016-05-31T11:40:31Z
0926-860X
641825
http://hdl.handle.net/2445/99085
This work reports the production of di-n-butyl ether (DNBE) by means of 1-butanol dehydration in the liquid phase on acidic ion-exchange resins. Dehydration experiments were performed at 150 ºC and 40 bar on 13 styrene-codivinylbenzene ion exchangers of different morphology. By comparing 1-butanol conversions to DNBE and initial reaction rates it is concluded that oversulfonated resins are the most active catalysts for 1-butanol dehydration reaction whereas gel-type resins that swell significantly in the reaction medium as well as the macroreticular thermostable resin Amberlyst-70 are the most selective to DNBE. The highest DNBE yield was achieved on Amberlyst 36. The influence of typical 1-butanol impurities on the dehydration reaction were also investigated showing that the presence of 2-methyl-1-propanol (isobutanol) enhances the formation of branched ethers such as 1-(1-methylpropoxy) butane and 1-(2-methylpropoxy) butane, whereas the presence of ethanol and acetone yields ethyl butyl ether and, to a much lesser extent, diethyl ether.
11 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.apcata.2014.05.017
Applied Catalysis A-General, 2014, vol. 482, p. 38-48
http://dx.doi.org/10.1016/j.apcata.2014.05.017
(c) Elsevier B.V., 2014
info:eu-repo/semantics/openAccess
Èters
Resines de bescanvi iònic
Catàlisi
Alcohol butílic
Ethers
Ion exchange resins
Catalysis
Butanol
Ion exchange resins as catalysts for the liquid-phase dehydration of 1-butanol to di-n-butyl ether
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2622762017-05-23T04:50:14Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorBringue Tomás, Roger
authorRamírez Rangel, Eliana
authorIborra Urios, Montserrat
authorTejero Salvador, Xavier
authorCunill García, Fidel
2016-05-31T12:13:47Z
2016-05-31T12:13:47Z
2013-05-06
2016-05-31T12:13:53Z
0021-9517
620951
http://hdl.handle.net/2445/99091
Ethyl-octyl ether (EOE) liquid phase synthesis from ethanol and 1-octanol over ion-exchange resins is feasible at 423K, though di-ethyl ether and di-n-octyl ether were also formed. The influence of the catalyst morphology on the reaction was checked by testing twenty-two acidic resins. Gel-type resins of low crosslinking degree yielded the higher amounts of EOE, whereas macroreticular ones of high crosslinking degree gave mainly di-ethyl ether. Ethanol conversion highly depends on the resin acid capacity, [H+], whereas 1-octanol conversion and selectivity to EOE depends on the specific volume of swollen polymer, Vsp, and porosity. The variation of ethanol and 1-octanol conversion, selectivity to EOE with respect to both alcohols as well as ethers TOF as a function of [H+]/Vsp suggests that a part of the active sites does not take part in the EOE synthesis reaction on highly cross-linked resins. Amberlyst 70 could be interesting in industry due to its selectivity to EOE and higher thermal stability
15 p.
application/pdf
eng
Academic Press
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.jcat.2013.03.006
Journal of Catalysis, 2013, vol. 304, p. 7-21
http://dx.doi.org/10.1016/j.jcat.2013.03.006
(c) Academic Press, 2013
info:eu-repo/semantics/openAccess
Resines de bescanvi iònic
Èters
Alcohol
Ion exchange resins
Ethers
Alcohol
Influence of acid ion-exchange resins morphology in swollen state on the synthesis of ethyl octyl ether from ethanol and 1-octanol
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2622702017-05-23T04:50:15Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorBringue Tomás, Roger
authorCadenas, Madelin
authorFité Piquer, Carles
authorIborra Urios, Montserrat
authorCunill García, Fidel
2016-05-31T12:48:21Z
2016-05-31T12:48:21Z
2012-07-23
2016-05-31T12:48:26Z
1385-8947
616399
http://hdl.handle.net/2445/99092
Oligomerization of 1-octene is a feasible alternative to improve the properties and the quality of fuels and lubricants oils. The performance of macroreticular ion-exchange resins as catalysts for such reaction has been evaluated. The experimental setup consisted of a batch stirred-tank reactor that operated at 353-393 K and 2 MPa. 1-Octene conversion was practically complete and the selectivity to double-bond isomerization and dimers after 6 h at 373 K was up to 95% and 12%, respectively. The accessible acidity of the catalysts was the most important structural parameter for these reactions. Selectivity to dimers and branched isomers increased with increasing temperature. Cracking compounds were not detected at all. The theoretical equations derived from the proposed kinetic model fit well the experimental results.
9 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.cej.2012.06.089
Chemical Engineering Journal, 2012, vol. 207-208, p. 226-234
http://dx.doi.org/10.1016/j.cej.2012.06.089
(c) Elsevier B.V., 2012
info:eu-repo/semantics/openAccess
Resines de bescanvi iònic
Cinètica enzimàtica
Catàlisi
Ion exchange resins
Enzyme kinetics
Catalysis
Study of the oligomerization of 1-octene catalyzed by macroreticular ion-exchange resins
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2855472017-05-23T04:50:15Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorSimón, Francesc Xavier
authorRudé i Payró, Elisabet
authorLlorens Llacuna, Joan
authorBaig, Sylvie
2013-09-06T11:03:00Z
2013-09-06T11:03:00Z
2013
2013-09-06T11:03:01Z
0049-6979
623752
http://hdl.handle.net/2445/45683
In the present study, we examined seawater biofiltration in terms of adenosine triphosphate (ATP) and turbidity. A pilot biofilter continuously fed with fresh seawater reduced both turbidity and biological activity measured by ATP. Experiments operated with an empty bed contact time (EBCT) of between 2 and 14 min resulted in cellular ATP removals of 32% to 60% and turbidity removals of 38% to 75%. Analysis of the water from backwashing the biofilter revealed that the first half of the biofilter concentrated around 80% of the active biomass and colloidal material that produces turbidity. By reducing the EBCT, the biological activity moved from the first part of the biofilter to the end. Balances of cellular ATP and turbidity between consecutive backwashings indicated that the biological activity generated in the biofilter represented more than 90% of the detached cellular ATP. In contrast, the trapped ATP was less than 10% of the overall cellular ATP detached during the backwashing process. Furthermore, the biological activity generated in the biofilter seemed to be more dependent on the elapsed time than the volume filtered. In contrast, the turbidity trapped in the biofilter was proportional to the volume filtered, although a slightly higher amount of turbidity was found in the backwashing water; this was probably due to attrition of the bed medium. Finally, no correlations were found between turbidity and ATP, indicating that the two parameters focus on different matter. This suggests that turbidity should not be used as an alternative to cellular concentration.
28 p.
application/pdf
eng
Springer Science + Business Media
Versió postprint del document publicat a: http://dx.doi.org/10.1007/s11270-013-1568-3
Water, Air, & Soil Pollution, 2013, vol. 224, p. 1568-1-1568-11
http://dx.doi.org/10.1007/s11270-013-1568-3
(c) Springer Science + Business Media, 2013
info:eu-repo/semantics/openAccess
Aigua de mar
Biodegradació
Biofilms
Biomassa
Enginyeria química
Contaminació de l'aigua
Seawater
Biodegradation
Biofilms
Biomass
Chemical engineering
Water pollution
Study of seawater biofiltration by measuring adenosine triphosphate (ATP) and turbidity
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2624212017-05-23T04:50:16Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorBringue Tomás, Roger
authorRamírez, Eliana
authorFité Piquer, Carles
authorIborra Urios, Montserrat
authorTejero Salvador, Xavier
2016-06-07T07:48:04Z
2016-06-07T07:48:04Z
2011-05-19
2016-06-07T07:48:09Z
0888-5885
596950
http://hdl.handle.net/2445/99289
The effect of water on the kinetics of the liquid-phase dehydration of 1-pentanol to di-n-pentyl ether (DNPE) and water over Amberlyst 70 is revisited. To explain the strong inhibitor effect of water, two approaches were compared. First, a model stemming from a Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism was used, wherein the inhibitor effect of water was explained by the competitive adsorption of water and pentanol. Second, a modified Eley-Rideal (ER) model was used that includes an inhibition factor, in which a Freundlich-like function is used to explain the inhibitor effect of water by blocking the access of pentanol to the active centers. Both models fitted data quite well, although the best results were obtained with the modified ER model. The activation energy was 118.7 ± 0.2 kJ/mol for the LHHW model and 114.0 ± 0.1 kJ/mol for the modified ER one.
9 p.
application/pdf
eng
American Chemical Society
Versió postprint del document publicat a: http://dx.doi.org/10.1021/ie1025776
Industrial & Engineering Chemistry Research, 2011, vol. 50, num. 13, p. 7911-7919
http://dx.doi.org/10.1021/ie1025776
(c) American Chemical Society , 2011
info:eu-repo/semantics/openAccess
Èters
Adsorció
Catàlisi
Ethers
Adsorption
Catalysis
Kinetics of 1-pentanol etherification without water removal
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2624222017-05-23T04:50:17Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorParets, Lídia
authorAlechaga Silva, Élida
authorNúñez Burcio, Oscar
authorSaurina, Javier
authorHernández Cassou, Santiago
authorPuignou i Garcia, Lluís
2016-06-07T14:55:29Z
2016-06-07T14:55:29Z
2016-04-29
2016-06-07T14:55:34Z
1759-9660
656341
http://hdl.handle.net/2445/99325
Ultrahigh pressure liquid chromatography-atmospheric pressure photoionization-tandem mass spectrometry (UHPLC-APPI-MS/MS) was applied to the analysis and authentication of fruit-based products and pharmaceutical preparations. Two sub-2 µm C18 reversed-phase columns, Syncronis (100x2.1 mm, 1.7 µm) and Hypersil Gold (50x2.1 mm, 1.9 µm) were proposed under gradient elution with 0.1 % formic acid aqueous solution and methanol mobile phases for the determination of 29 polyphenols, allowing to obtain polyphenolic profiles in less than 13.5 and 23.5 min, respectively. Several atmospheric pressure ionization (API) sources (H-ESI, APCI, APPI) were compared. For dopant-assisted APPI, four organic solvents, toluene, acetone, chlorobenzene and anisole were evaluated as dopants. Both, H-ESI and acetone-assisted APPI were selected as the best ionization sources for the analysis of targeted polyphenols. Acceptable sensitivity (LOD values down to 0.5 µg kg-1 in the best of cases), linearity (r2 higher than 0.995) and good precision (RSD values lower than 15.1%) and trueness (relative errors lower than 10.2%) were obtained with both UHPLC-API-MS/MS methods. A simple extraction procedure, consisting of a sample sonication with acetone/water/hydrochloric acid (70:29.9:0.1 v/v/v) and centrifugation, was used. The proposed UHPLC-ESI-MS/MS and UHPLC-APPI-MS/MS methods with both C18 reversed-phase columns were then applied to the analysis of 32 grape-based and cranberry-based natural products and pharmaceutical preparations. Polyphenolic profiles data were then analyzed by principal component analysis (PCA) to extract information of the most significant data contributing to classification of natural extracts according to the type of fruit.
16 p.
application/pdf
eng
Royal Society of Chemistry
Reproducció del document publicat a: http://dx.doi.org/10.1039/C6AY00929H
Analytical Methods, 2016, vol. 8, p. 4363-4378
http://dx.doi.org/10.1039/C6AY00929H
cc-by (c) Parets, Lídia et al., 2016
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by/3.0/es">http://creativecommons.org/licenses/by/3.0/es</a>
Cromatografia de líquids
Polifenols
Liquid chromatography
Polyphenols
Ultrahigh pressure liquid chromatography-atmospheric pressure photoionization-tandem mass spectrometry for the determination of polyphenolic profiles in the characterization and classification of cranberry-based pharmaceutical preparations and natural extracts.
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2628622017-05-23T04:50:19Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorCabot Canyelles, Joan Marc
authorSubirats i Vila, Xavier
authorFuguet i Jordà, Elisabet
authorRosés Pascual, Martí
2016-06-17T10:58:56Z
2016-06-17T10:58:56Z
2014-07-18
2016-06-17T10:59:01Z
1848-7718
642657
http://hdl.handle.net/2445/99599
n 1997Valkó et al. developed a generic fast gradient HPLC method, based on the calculation of the Chromatographic Hydrophobicity Index (CHI) from the gradient retention times, in order to measure lipophilicity. We have employedthe correlations between CHI and log Po/wand adapted the rapid gradient HPLC method to UHPLC obtaining excellent resolution and repeatability in a short analysis time (<4min). log Po/wvalues can be easily obtained from these CHI measurementsbut, unfortunately, these correlations are only valid for non-ionized compounds. Consequently, in order to determine the effective log Po/wvalue at a particular pH, afast high-throughput method for pKadeterminationwas required. The IS-CE method, based on the use of internal standards (IS) and capillaryelectrophoresis(CE),is a fast and attractive alternative to other methods for pKadetermination,since itoffers multiple advantages compared to them: low amounts of test compounds and reagents are needed, high purity is not required, specific interactions between test compounds and buffers are corrected, etc. In addition, it allows the determination of a pKavalue in less than 5 minutes. Both CHI and IS-CE have beencombined in order to describe a high throughput alternative in thedetermination ofthe lipophilicity profiles of bioactive compounds.
9 p.
application/pdf
eng
IAPC Publishing
Reproducció del document publicat a: http://dx.doi.org/10.5599/admet.2.2.44
ADMET & DMPK, 2014, vol. 2, num. 2, p. 98-106
http://dx.doi.org/10.5599/admet.2.2.44
cc-by (c) Cabot Canyelles, Joan Marc et al., 2014
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by/3.0/es">http://creativecommons.org/licenses/by/3.0/es</a>
Disseny de medicaments
Funció d'acidesa
Medicaments
Drug design
Acidity function
Drugs
High throughput determination log Po/w/pKa/log Do/w of drugs by combination of UHPLC and CE methods
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2628632017-05-23T04:50:20Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorLoizzo, Monica R.
authorPacetti, Deborah
authorLucci, Paolo
authorNúñez Burcio, Oscar
authorMenichini, Francesco
authorFrega, Natale G.
authorTundis, Rosa
2016-06-17T12:09:41Z
2016-07-03T22:01:24Z
2015-07-03
2016-06-17T12:09:46Z
0921-9668
653279
http://hdl.handle.net/2445/99604
A comparative analysis of ethanol extracts from peel, pulp and seed of Prunus persica var. platycarpa (Tabacchiera peach) was done. The total phenols, flavonoids and carotenoids content as well as the antioxidant properties were evaluated. Peach pulp extract was characterized by the highest total phytonutrients content and exhibited the highest antioxidant activity in all in vitro assays. Interestingly, pulp extract showed IC50 values of 2.7 and 2.2 g/mL at 30 and 60 minutes of incubation, respectively using -carotene bleaching test. A remarkable result was also obtained by using Fe-chelating assay (IC50 of 2.9 g/mL vs 1.3 g/mL for positive control BHT). Pulp extract was subjected to liquid chromatography-electrospray-tandem mass spectrometry (HPLC-ESI-MS/MS). Six main compounds, namely gallic acid, protocatechuic acid, protocatechualdehyde, chlorogenic acid, p-coumaric acid, and ferulic acid, were identified. Overall, the results suggest that Prunus persica var. platycarpa displays a good antioxidant activity and its consumption could be promoted
7 p.
application/pdf
eng
Springer Verlag
Versió postprint del document publicat a: http://dx.doi.org/10.1007/s11130-015-0498-1
Plant Foods for Human Nutrition, 2015, vol. 70, num. 3, p. 331-337
http://dx.doi.org/10.1007/s11130-015-0498-1
(c) Springer Verlag, 2015
info:eu-repo/semantics/openAccess
Fenols
Arbres fruiters
Antioxidants
Phenols
Fruit trees
Antioxidants
Prunus persica var. platycarpa (Tabacchiera Peach): bioactive compounds and antioxidant activity of pulp, peel and seed ethanolic extracts
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2628642017-05-23T04:50:21Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorBadia i Córcoles, Jordi Hug
authorFité Piquer, Carles
authorBringue Tomás, Roger
authorIborra Urios, Montserrat
authorCunill García, Fidel
2016-06-17T12:26:25Z
2016-08-20T22:01:19Z
2015-08-20
2016-06-17T12:26:30Z
1022-5528
654738
http://hdl.handle.net/2445/99605
Although macroreticular acidic ion-exchange resins have been widely used as catalysts in the industrial world for decades, their catalytic behavior is still far from being completely understood at a molecular level. Several characterization techniques coexist, which provide information about their properties. Only few of these techniques give an actual picture of their working-state features when swollen in anhydrous polar reactive media such as in etherification processes, where they are extensively used. The inverse steric exclusion chromatography technique, based on modeling the micropores structure, or gel phase, as a set of discrete volume fractions with a characteristic polymer chain density, constitutes an appropriate procedure to assess the morphology of ion-exchangers in the swollen state. Present work proposes an empirical model to correlate the properties of the volume fractions with their catalytic activity in the etherification reaction rates of isobutene by addition of C1 to C4 linear primary alcohols. Sixteen different macroreticular acidic ion-exchange catalysts, both commercial and lab-made, have been used, which differ in acid capacity, sulfonation type, cross linking degree and swollen-phase volume fractions distribution. Experimental reaction rates have been expressed as a sum of contributions of each individual volume fraction. The contribution of each polymer volume fraction corresponds to the product of the catalyst acidity, the characteristic volume fraction within the gel phase of the catalyst, and a specific turnover frequency (TOF) of that fraction. Accessibility of the reacting alcohol, expressed in terms of the Ogston coefficient, has been also included in the empirical dependency equation presented in this work.
14 p.
application/pdf
eng
Springer Verlag
Versió postprint del document publicat a: http://dx.doi.org/10.1007/s11244-015-0460-3
Topics in Catalysis, 2015, vol. 58, num. 14, p. 919-932
http://dx.doi.org/10.1007/s11244-015-0460-3
(c) Springer Verlag, 2015
info:eu-repo/semantics/openAccess
Èters
Resines de bescanvi iònic
Alcohols
Catàlisi
Ethers
Ion exchange resins
Alcohols
Catalysis
Catalytic activity and accessibility of acidic ion-exchange resins in liquid-phase etherification reactions
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2665052017-05-23T04:50:23Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorSubirats i Vila, Xavier
authorYuan, Hui-Ping
authorChaves, Verónica
authorMarzal, Núria
authorRosés Pascual, Martí
2016-07-27T08:34:40Z
2017-04-29T22:01:14Z
2016-04-29
2016-07-27T08:34:45Z
0173-0835
661985
http://hdl.handle.net/2445/101321
In the present work, several MEEKC systems are studied to assess their suitability for lipophilicity determination of acidic, neutral, and basic compounds. Thus, several microemulsion compositions over a wide range of pH values (from 2.0 to 12.0), containing heptane, 1−butanol and different types and amounts of surfactant (SDS or sodium cholate: from 1.3 to 3.3%) are characterized using Abraham's solvation model. The addition of acetonitrile (up to 10%) is also studied, since it increases the resolution of the technique for the most lipophilic compounds. The system coefficients obtained are very similar to those of the 1−octanol/water, used as the reference lipophilicity index, allowing simple and linear correlations between the 1−octanol/water partition values (log Po/w) and MEEKC mass distribution ratios (log kMEEKC). Variations in the microemulsion composition (aqueous buffer, surfactant, concentration of ACN) did not significantly affect the similarity of the MEEKC systems to log Po/w partition.
7 p.
application/pdf
eng
Wiley-VCH
Versió postprint del document publicat a: http://dx.doi.org/10.1002/elps.201600080
Electrophoresis, 2016, vol. 37, num. 14, p. 2010-2016
http://dx.doi.org/10.1002/elps.201600080
(c) Wiley-VCH, 2016
info:eu-repo/semantics/openAccess
Electroforesi capil·lar
Cromatografia de líquids
Lipofília
Capillary electrophoresis
Liquid chromatography
Lipophilicity
Microemulsion electrokinetic chromatography as a suitable tool for lipophilicity determination of acidic, neutral, and basic compounds
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2668632017-05-23T04:50:25Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorPuigventós, Lídia
authorNúñez Burcio, Oscar
authorSaurina, Javier
2016-09-20T16:56:28Z
2016
2016-09-20T16:56:33Z
info:eu-repo/date/embargoEnd/2017-12-31
1573-4110
657139
http://hdl.handle.net/2445/101986
This work introduces the topic of the authentication of cranberry-based products and the detection and quantification of possible adulterations with other raw materials of lower quality. For such a purpose, genuine and adulterated cranberry samples were analyzed by reversed-phase HPLC with UV detection. Sample components were separated using an elution gradient based on 0.1% (v/v) formic acid aqueous solution and methanol as the components of the mobile phase. Chromatograms were recorded at 280, 370 and 520 nm. Data resulting from the injection of pure and adulterated samples, consisting of chromatographic fingerprints at each detection wavelength, were analyzed chemometrically. Preliminary studies by Principal Component Analysis showed that the sample extracts were clearly distributed depending on the extent of adulteration. Data was further treated by Partial Least Square regression to determine the percentages of grape contamination. It was found that even mixture samples containing low percentages of grape could be distinguished from genuine cranberry extracts. Besides, results obtained were highly satisfactory, with overall quantification errors lower than 5%. As a conclusion, the method proposed here resulted in an excellent approach to carry out the authentication of cranberry-based products relying on polyphenolic fingerprints.
10 p.
application/pdf
eng
Bentham Science Publishers
Versió postprint del document publicat a: http://dx.doi.org/10.2174/1573411012666160216220526
Current Analytical Chemistry, 2016, vol. 12
http://dx.doi.org/10.2174/1573411012666160216220526
(c) Bentham Science Publishers, 2016
info:eu-repo/semantics/embargoedAccess
Cromatografia de líquids
Quimiometria
Polifenols
Química dels aliments
Liquid chromatography
Chemometrics
Polyphenols
Food composition
HPLC fingerprints for the authentication of cranberry-based products based on multivariate calibration approaches
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/1838432017-06-01T00:46:49Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorJunza Martínez, Alexandra
authorAmatya, Rameshwari
authorBarrón Bueno, Dolores
authorBarbosa Torralbo, José
2012-04-26T10:03:48Z
2012-04-26T10:03:48Z
2011
1570-0232
607387
http://hdl.handle.net/2445/24558
The aim of this study was to develop and validate an analytical method to simultaneously determine European Union-regulated beta-lactams (penicillins and cephalosporins) and quinolones in cow milk. The procedure involves a new solid phase extraction (SPE) to clean-up and pre-concentrate the three series of antibiotics before analysis by liquid chromatography¿tandem mass spectrometry (LC-MS/MS) and ultra-high-performance liquid chromatography¿tandem mass spectrometry (UPLC-MS/MS). LC-MS/MS and UPLC-MS/MS techniques were also compared. The method was validated according to the Directive 2002/657/EC and subsequently applied to 56 samples of raw cow milk supplied by the Laboratori Interprofessional Lleter de Catalunya (ALLIC) (Laboratori Interprofessional Lleter de Catalunya, Control Laboratory Interprofessional of Milk of Catalunya).
41 p.
application/pdf
eng
Elsevier
Versió preprint del document publicat a: http://dx.doi.org/10.1016/j.jchromb.2011.07.018
Journal of Chromatography B, 2011, vol. 879, núm. 25, p. 2601¿2610
http://dx.doi.org/10.1016/j.jchromb.2011.07.018
(c) Elsevier, 2011
info:eu-repo/semantics/openAccess
Llet
Quinolones
Química analítica
Milk
Quinolone antibacterial agents
Analytical chemistry
Comparative study of the LC-MS/MS and UPLC-MS/MS for the multi-residue analysis of quinolones, penicillins and cephalosporins in cow milk, and validation according to the regulation 2002/657/EC
info:eu-repo/semantics/article
info:eu-repo/semantics/submittedVersion
oai:recercat.cat:2072/2138912017-06-01T00:49:04Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorJunza Martínez, Alexandra
authorAmatya, Rameshwari
authorPérez-Burgos, Rafael
authorGokce, Gultekin
authorGrzelak, Edyta
authorBarrón Bueno, Dolores
authorBarbosa Torralbo, José
2013-07-09T11:42:10Z
2013-07-09T11:42:10Z
2010
2013-07-09T11:42:10Z
1223-7221
586520
http://hdl.handle.net/2445/44669
The aim of this work is to optimize and validate methods for the multiresidue determination of series of families of antibiotics as quinolones, penicillins and cephalosporins included in European regulation in food samples using LC-MS/MS. Different extraction techniques and clean-up applied to antibiotics in meat were compared. The quality parameters were established according with EU guideline. The developed method was applied to 49 positive raw milk samples from animal medicated with different antibiotics; the 63% of the analyzed samples were found to be compliant. ___________________________________________________________________________________________
14 p.
application/pdf
eng
Universitatea Ovidius
Ovidius University Annals of Chemistry, 2010, vol. 21, num. 2, p. 109-122
(c) Universitatea Ovidius, 2010
info:eu-repo/semantics/openAccess
Quinolones
Penicil·lina
Teixits (Histologia)
Llet
Cefalosporines
Quinolone antibacterial agents
Penicillin
Tissues
Milk
Cephalosporines
Residues of b-lactams and quinolones in tissues and milk samples. Confirmatory analysis by liquid chromatography-mass spectrometry
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2734722017-06-09T00:57:04Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorAviñó Andrés, Anna
authorMazzini, Stefania
authorFàbrega i Claveria, Ma. Carme
authorPeñalver, Pablo
authorGargallo Gómez, Raimundo
authorMorales, J.C.
authorEritja i Casadellà, Ramon
2017-02-16T11:54:21Z
2016-10-02
2017-02-16T11:54:22Z
info:eu-repo/date/embargoEnd/2017-10-02
0304-4165
667636
http://hdl.handle.net/2445/107055
Background Guanine-rich oligonucleotides are capable of forming tetrahelical structures known as G-quadruplexes with interesting biological properties. We have investigated the effects of site-specific substitution in the loops and in the tetrads model G-quadruplexes using thymine glycol nucleic acid (GNA) units, l-thymidine and 8-Br-2′-deoxyguanosine. Methods Modified oligonucleotides were chemically synthesized and spectroscopic techniques were used to determine the relative stability of the modified G-quadruplex. The double 8-BrdG-modified quadruplexes were further characterized by Nuclear Magnetic Resonance. Binding to thrombin of selected quadruplex was analyzed by gel electrophoresis retention assay. Results The most interesting results were found with a 8-bromoG substitution that had the larger stabilization of the quadruplex. NMR studies indicate a tight relationship between the loops and the tetrads to accommodate 8-bromoG modifications within the TBA. Conclusions The substitutions of loop positions with GNA T affect the TBA stability except for single modification in T7 position. Single l-thymidine substitutions produced destabilization of TBA. Larger changes on quadruplex stability are observed with the use of 8-bromoG finding a single substitution with the highest thermal stabilization found in thrombin binding aptamers modified at the guanine residues and having good affinity for thrombin. Double 8-BrdG modification in anti positions of different tetrads produce a conformational flip from syn to anti conformation of 8-Br-dG to favor loop-tetrad interaction and preserve the overall TBA stability.
29 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: https://doi.org/10.1016/j.bbagen.2016.09.030
Biochimica et Biophysica Acta-General Subjects, 2017, vol. 1861, num. 5, Part B, p. 1205-1212
https://doi.org/10.1016/j.bbagen.2016.09.030
cc-by-nc-nd (c) Elsevier B.V., 2016
info:eu-repo/semantics/embargoedAccess
<a href="http://creativecommons.org/licenses/by-nc-nd/3.0/es">http://creativecommons.org/licenses/by-nc-nd/3.0/es</a>
Biologia molecular
Bioquímica
Oligonucleòtids
G-estructures
Molecular biology
Biochemistry
Oligonucleotides
G-structures
The effect of l-thymidine, acyclic thymine and 8-bromoguanine on the stability of model G-quadruplex structures
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2397342017-07-18T08:02:21Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorCarneado Moreno, Sergio
authorHernández-Nataren, E.
authorLópez Sánchez, José Fermín
authorSahuquillo Estrugo, Àngels
2014-09-23T07:27:33Z
2014-09-23T07:27:33Z
2014-06-18
2014-09-23T07:27:33Z
0308-8146
643388
http://hdl.handle.net/2445/57563
The influence of storage time and temperature on Sb migration from PET bottles into mineral water was studied in short-term tests lasting up to 15 days and long-term studies lasting up to 220 days. Samples purchased were stored in three different coloured bottles: clear (CL), light blue (LB) and dark blue (DB). Sb migration was assayed by HG-AFS for total determination and HPLC-ICP-MS for speciation analysis. Migration studies showed that waters stored at 4 and 20 oC were not subject to Sb migration. At 40 oC there was a significant increase in Sb concentration, although the maximum limit established by the European Union (5.0 ug/L) was not exceeded, whereas at 60 oC samples were subject to considerable Sb migration after 30 days of storage. In this case, the maximum limit established by the European Union was exceeded and both Sb (V) and Sb (III) were detected.
29 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.foodchem.2014.06.041
Food Chemistry, 2014, vol. 166, p. 544-550
http://dx.doi.org/10.1016/j.foodchem.2014.06.041
(c) Elsevier B.V., 2014
info:eu-repo/semantics/openAccess
Aigües minerals
Tereftalat de polietilè
Envasos
Química analítica
Semimetalls
Contaminació de l'aigua
Mineral waters
Polyethylene terephthalate
Containers
Analytical chemistry
Semimetals
Water pollution
Migration of antimony from polyethylene terephthalate used in mineral water bottles.
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2900212017-07-18T08:02:24Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorGrijalvo, Santiago
authorAlagia, Adele
authorGargallo Gómez, Raimundo
authorEritja i Casadellà, Ramon
2017-07-17T11:28:27Z
2017-07-17T11:28:27Z
2016-08-04
2017-07-17T11:28:27Z
2046-2069
664383
http://hdl.handle.net/2445/113893
Oligonucleotides carrying cationic peptides have been used to improve hybridization and cellular uptake of oligonucleotides. In this study, a series of four cationic amino acid derivatives were covalently linked at the 3′-termini with the objective of modifying the Tetrahymena telomeric repeat sequence d(TGGGGT). This led to the synthesis of a small cationic G-quadruplex-forming oligonucleotide series containing lysine, ornithine, homo-arginine and arginine moieties. The preparation of the appropriate solid-supports afforded the synthesis of 3′-lysine and 3′-ornithine oligonucleotides which were converted to homo-arginine and arginine conjugates through post-synthetic modifications. Circular dichroism and thermal denaturation experiments confirmed that the presence of the four cationic residues did not affect the formation of stable parallel G-quadruplex structures. Afterwards, a phosphorothioate oligonucleotide targeting Renilla luciferase mRNA was prepared at the 5′-termini of this telomeric sequence which afforded a series of phosphorothioate oligonucleotide/[d(TG4T)]4 hybrid constructs modified with lysine, ornithine, homo-arginine and arginine units after incubation. In addition, the phosphodiester/phosphorothioate mixed backbone contributed to the degradation of the G-quadruplex moiety by exonucleases liberating the antisense sequence. Cell culture analysis of gene expression showed that the formation of self-assembled G-quadruplex nanostructures did not disrupt the antisense mechanism and therefore were able to induce luciferase gene inhibition in mammalian cells without using cationic lipids. Flow cytometry analyses confirmed that fluorescently labelled antisense G4-quadruplex nanostructures were efficiently taken up by HeLa cells. These results suggest that G-quadruplex nanostructures may be used to improve cellular uptake of therapeutic oligonucleotides. © 2016 The Royal Society of Chemistry.
11 p.
application/pdf
eng
Royal Society of Chemistry
Reproducció del document publicat a: https://doi.org/10.1039/c6ra15336d
RSC Advances, 2016, vol. 6, p. 76099-76109
https://doi.org/10.1039/c6ra15336d
cc-by (c) Grijalvo, Santiago et al., 2016
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by/3.0/es">http://creativecommons.org/licenses/by/3.0/es</a>
Oligonucleòtids
G-estructures
Nanoestructures
Oligonucleotides
G-structures
Nanostructures
Cellular uptake studies of antisense oligonucleotides using G-quadruplex- nanostructures. The effect of cationic residue on the biophysical and biological properties
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
oai:recercat.cat:2072/2408422017-07-18T08:02:25Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorZmozinski, Ariane V.
authorCarneado Moreno, Sergio
authorIbáñez Palomino, Carmen
authorSahuquillo Estrugo, Àngels
authorLópez Sánchez, José Fermín
authorDa Silva, Márcia M.
2014-10-14T07:46:44Z
2014-10-14T07:46:44Z
2014-06-09
2014-10-14T07:46:44Z
0956-7135
643387
http://hdl.handle.net/2445/58572
This paper reports the method development for the simultaneous determination of methylmercury MeHgþ) and inorganic mercury (iHg) species in seafood samples. The study focused on the extraction and quantification of MeHgþ (the most toxic species) by liquid chromatography coupled to on-line UV irradiation and cold vapour atomic fluorescence spectroscopy (LC-UV-CV-AFS), using HCl 4 mol/L as the extractant agent. Accuracy of the method has been verified by analysing three certified reference materials and different spiked samples. The values found for total Hg and MeHgþ for the CRMs did not differ significantly from certified values at a 95% confidence level, and recoveries between 85% and 97% for MeHgþ, based on spikes, were achieved. The detection limits (LODs) obtained were 0.001 mg Hg/kg for total mercury, 0.0003 mg Hg/kg for MeHgþ and 0.0004 mg Hg/kg for iHg. The quantification limits (LOQs) established were 0.003 mg Hg/kg for total mercury, 0.0010 mg Hg/kg for MeHgþ and 0.0012 mg Hg/kg for iHg. Precision for each mercury species was established, being 12% in terms of RSD in all cases. Finally, the developed method was applied to 24 seafood samples from different origins and total mercury contents. The concentrations for Total Hg, MeHg and iHg ranged from 0.07 to 2.33, 0.003-2.23 and 0.006-0.085 mg Hg/kg, respectively. The established analytical method allows to obtain results for mercury speciation in less than 1 one hour including both, sample pretreatment and measuring step.
36 p.
application/pdf
eng
University College London, Faculty of Mathematical and Physical Sciences, Department of Mathematics
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.foodcont.2014.05.054
Food Control, 2014, vol. 46, p. 351-359
http://dx.doi.org/10.1016/j.foodcont.2014.05.054
(c) University College London, Faculty of Mathematical and Physical Sciences, Department of Mathematics, 2014
info:eu-repo/semantics/openAccess
Mercuri
Marisc
Tests de toxicitat
Química analítica
Mercury
Seafood
Toxicity testing
Analytical chemistry
Method development for the simultaneous determination of methylmercury and inorganic mercury in seafood
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2522312017-07-18T08:02:25Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorCarneado Moreno, Sergio
authorPeró Gascón, Roger
authorIbáñez Palomino, Carmen
authorLópez Sánchez, José Fermín
authorSahuquillo Estrugo, Àngels
2015-07-13T08:33:34Z
2016-02-09T23:01:42Z
2015-02-09
2015-07-13T08:33:34Z
1759-9660
648482
http://hdl.handle.net/2445/66291
This paper reports a method developed for the simultaneous determination of methylmercury (MeHg+) and mercury(II) (Hg2+) species in water by liquid chromatography coupled to online UV irradiation and cold vapour atomic fluorescence spectrometry (LC-UV-CV-AFS) after online short-column preconcentration. This work focused on systematic studies of several variables to establish the maximum species recoveries, preconcentration factors and good reproducibility. The optimum results obtained were the following: 0.07 mmol L 1 2-mercaptoethanol as a complexing agent, precolumn conditioning with the mobile phase: a mixture of 80% of methanol (MeOH) and 20% of the following buffer: 0.0015 mol L 1 ammonium pyrrolidine dithiocarbamate (APDC) and 0.01 mol L 1 ammonium acetate (NH4CH3COO) at pH 5.5, 2 cm precolumn length and 2 mL min 1 sample flow. This method was applied to three water samples with different mineralisation contents. Various tests, based on spikes, were performed on each sample. A breakthrough volume of 4 mL was found. The recovery values of 72 3% and 81 5% for MeHg+ and Hg2+, respectively, were obtained regardless of the matrix composition, and the PF values were 30 and 32 for MeHg+ and Hg2+, respectively. The accuracy of the preconcentration method was verified by analysing a certified reference material. The detection limits (LDs) obtained were 15 ng L 1 for MeHg+ and 2 ng L 1 for Hg2+. The quantification limits (LQs) were 50 ng L 1 for both species. The established analytical online preconcentration method is suitable for the quantification of mercury species in a wide range of environmental waters.
8 p.
application/pdf
eng
Royal Society of Chemistry
Versió postprint del document publicat a: http://dx.doi.org/10.1039/c4ay02929a
Analytical Methods, 2015, vol. 7, p. 2699-2706
http://dx.doi.org/10.1039/c4ay02929a
(c) Carneado, S. et al., 2015
info:eu-repo/semantics/openAccess
Mercuri
Cromatografia de líquids
Contaminació de l'aigua
Metilmercuri
Mercury
Liquid chromatography
Water pollution
Methylmercury
Mercury (II) and methylmercury determination in waters by liquid chromatography hyphenated to cold vapour atomic fluorescence spectrometry after online short-column preconcentration
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2612602017-07-18T08:02:26Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorPérez Ràfols, Clara
authorSerrano i Plana, Núria
authorDíaz Cruz, José Manuel
authorAriño Blasco, Cristina
authorEsteban i Cortada, Miquel
2016-04-28T09:38:01Z
2016-04-28T09:38:01Z
2015-03-18
2016-04-28T09:38:06Z
1040-0397
646609
http://hdl.handle.net/2445/97965
The suitability of mercury films on commercial screen-printed electrodes for the analysis of heavy metal ions is critically tested for the particular case of Pb(II)-ions. Although determination is possible by anodic stripping voltammetry with a reasonable detection limit (8.9 µg L-1), important drawbacks are noticed as a consequence of the heterogeneous deposition of mercury on the rough surface of screen-printed devices.
4 p.
application/pdf
eng
Wiley-VCH
Versió postprint del document publicat a: http://dx.doi.org/10.1002/elan.201500042
Electroanalysis, 2015, vol. 27, num. 6, p. 1345-1349
http://dx.doi.org/10.1002/elan.201500042
(c) Wiley-VCH, 2015
info:eu-repo/semantics/openAccess
Anàlisi electroquímica
Electrochemical analysis
Mercury films on commercial carbon screen-printed devices for the analysis of heavy metal ions: a critical evaluation
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2614052017-07-18T08:02:27Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorAstefanei, Alina
authorKok, Wim Th.
authorBäuerlein, Patrick
authorNúñez Burcio, Oscar
authorGalcerán Huguet, M. Teresa
authorDe Voogt, Pim
authorSchoenmakers, P.J.
2016-05-04T10:32:06Z
2017-07-04T22:01:32Z
2015-07-04
2016-05-04T10:32:22Z
0021-9673
653427
http://hdl.handle.net/2445/98258
Fullerenes are carbon nanoparticles with widespread biomedical, commercial and industrial applications. Attributes such as their tendency to aggregate and aggregate size and shape impact their ability to be transported into and through the environment and living tissues. Knowledge of these properties is therefore valuable for their human and environmental risk assessment as well as to control their synthesis and manufacture. In this work, asymmetrical flow-field flow fractionation (AF4) coupled to multi-angle light scattering (MALS) was used for the first time to study the size distribution of surface modified fullerenes with both polyhydroxyl and carboxyl functional groups in aqueous solutions having different pH (6.5-11) and ionic strength values (0-200 mM) of environmental relevance. Fractionation key parameters such as flow rates, flow programming, and membrane material were optimized for the selected fullerenes. The aggregation of the compounds studied appeared to be indifferent to changes in solution pH, but was affected by changes in the ionic strength. Polyhydroxy-fullerenes were found to be present mostly as 4 nm aggregates in water without added salt, but showed more aggregation at high ionic strength, with an up to 10-fold increase in their mean hydrodynamic radii (200 mM), due to a decrease in the electrostatic repulsion between the nanoparticles. Carboxy-fullerenes showed a much stronger aggregation degree in water (50 100 nm). Their average size and recoveries decreased with the increase in the salt concentration. This behavior can be due to enhanced adsorption of the large particles to the membrane at high ionic strength, because of their higher hydrophobicity and much larger particle sizes compared to polyhydroxy-fullerenes. The method performance was evaluated by calculating the run-to-run precision of the retention time (hydrodynamic radii), and the obtained RSD values were lower than 1 %. MALS measurements showed aggregate sizes that were in good agreement with the AF4 data. A comparison of the scattering radii from the MALS with the hydrodynamic radii obtained from the retention times in AF4 indicated that the aggregate shapes are far from spherical. TEM images of the fullerenes in the dry state also showed branched and irregular clusters.
10 p.
application/pdf
eng
Elsevier B.V.
Versió postprint del document publicat a: http://dx.doi.org/10.1016/j.chroma.2015.07.004
Journal of Chromatography A, 2015, vol. 1408, p. 197-206
http://dx.doi.org/10.1016/j.chroma.2015.07.004
cc-by-nc-nd (c) Elsevier B.V., 2015
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by-nc-nd/3.0/es">http://creativecommons.org/licenses/by-nc-nd/3.0/es</a>
Ful·lerens
Nanopartícules
Fullerenes
Nanoparticles
Characterization of aggregates of surface modified fullerenes by asymmetrical flow field-flow fractionation with multi-angle light scattering detection
info:eu-repo/semantics/article
info:eu-repo/semantics/acceptedVersion
oai:recercat.cat:2072/2900222017-07-18T08:02:28Zhdl_2072_171809
RECERCAT (Diposit de la Recerca de Catalunya)
Universitat de Barcelona
authorIborra Urios, Montserrat
authorRamírez Rangel, Eliana
authorBadia i Córcoles, Jordi Hug
authorBringue Tomás, Roger
authorTejero Salvador, Xavier
2017-06-13T16:57:40Z
2017-06-13T16:57:40Z
2017-07-10
2017-06-13T16:57:40Z
2014-5349
672031
http://hdl.handle.net/2445/112322
This work is focused on the implementation, development, documentation, analysis, and assessment of the flipped classroom methodology, by means of the just-in-time teaching strategy, for a pilot group (1 out of 6) in the subject 'Applied Computing' of both the Chemical and Materials Engineering Undergraduate Degrees of the University of Barcelona. Results show that this technique promotes self-learning, autonomy, time management as well as an increase in the effectiveness of classroom hours.
17 p.
application/pdf
eng
Omnia Science
Reproducció del document publicat a: https://doi.org/10.3926/jotse.244
Journal of Technology and Science Education, 2017, vol. 7, num. 2, p. 119-135
https://doi.org/10.3926/jotse.244
cc-by (c) Iborra Urios, Montserrat et al., 2017
info:eu-repo/semantics/openAccess
<a href="http://creativecommons.org/licenses/by/3.0/es">http://creativecommons.org/licenses/by/3.0/es</a>
Classe inversa
Aprenentatge actiu
Innovacions educatives
Ensenyament de la química
Flipped classroom
Active learning
Educational innovations
Chemistry education
Implementing the flipped classroom methodology to the subject 'applied computing' of two engineering degrees at the University of Barcelona
info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
0001-01-01T00:00:00Z/9999-12-31T23:59:59Z/hdl_2072_171808/mets/100