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Cerdanyola del Vallès, Spain

Licon C.C.,University of Castilla - La Mancha | Hurtado de Mendoza J.,Sailab | Maggi L.,University of Castilla - La Mancha | Berruga M.I.,University of Castilla - La Mancha | And 3 more authors.
International Dairy Journal | Year: 2012

An analytical method was developed for simultaneous determination of 50 volatiles in pressed ewe cheese using headspace sorptive extraction coupled to a thermal desorption and gas chromatography mass spectrometry. Method optimization was carried out in terms of chromatographic columns and conditions, stir bar size and holder, vial volume, salt content, sample weight, extraction temperature and time. The proposed method was validated showing good results in linearity (>0.98), precision (9-34%), recovery (58-120%), limit of detection (6-38ngkg -1) and limit of quantitation (75-150ngkg -1). The present method was also applied for the analysis of volatiles in ewes' milk cheese samples. © 2011 Elsevier Ltd. Source

Hurtado De Mendoza J.,Sailab | Maggi L.,University of Castilla - La Mancha | Bonetto L.,Sailab | Rodriguez Carmena B.,Laboratorio Of Salud Publica Madrid Salud | And 3 more authors.
Food Chemistry | Year: 2012

For the first time automated on-line solid phase extraction coupled to liquid chromatography tandem mass spectrometry was developed for the simultaneous determination of 13 antibiotics (sulfonamides and tetracyclines) in catfish. The method proposed was validated according to Commission Decision 2002/657/EC, showing good linearity between 2 and 350 μg kg-1, high recovery (80-99%) and reproducibility (13-20%) values, lower detection limits than 0.1 μg kg-1, and quantification limits under 2.4 μg kg-1 (between 39 and 84 times lower than the MRL fixed by the EU). Moreover, the proposed method was also used to determine sulfonamides and tetracyclines in 16 out of 107 samples, all previously analysed by microbiological screening that gave positive results. Five out of 13 antibiotics were found, having tetracycline the higher occurrence (10 samples); in all cases the concentrations were lower than the MRL established. © 2012 Elsevier Ltd. All rights reserved. Source

Maggi L.,University of Castilla - La Mancha | Maggi L.,Catholic University of the Sacred Heart | de Mendoza J.H.,Sailab | Zalacain A.,University of Castilla - La Mancha | And 3 more authors.
Food Analytical Methods | Year: 2012

A highly selective method was developed for the simultaneous determination of eight penicillins in catfish using automated on-line solid-phase extraction coupled to liquid chromatography-tandem mass spectrometry (XLC-MS/MS). The type of cartridge, equilibration sample volume, volume of solvent to carry the sample into the cartridge, and elution times were studied in order to optimize the XLC operating conditions. MS/MS conditions were also adjusted for better peak resolution. The present method was validated in agreement with the criteria of Commission Decision 2002/657/EC, showing a linear range from 2 to 350 μg kg -1 and regression coefficient higher than 0. 995 for the studied penicillins. Decision limits, calculated in the case of substances with no permitted limit, were lower than 0. 6 μg kg -1, and detection capability values were lower than 2. 0 μg kg -1. Samples spiked at 2. 0, 10. 0, and 50. 0 μg kg -1 showed high recovery (72-92%) and precision values lower than 20% except for amoxicillin. The present method was also applied for the analysis of penicillins in 30 catfish samples bought in local markets. © 2011 Springer Science+Business Media, LLC. Source

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