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San Juan de la Rambla, Spain

Ramos K.,Complutense University of Madrid | Gomez-Gomez M.M.,Complutense University of Madrid | Camara C.,Complutense University of Madrid | Ramos L.,IQOG
Talanta | Year: 2016

Silver migration from a commercial baby feeding bottle and a food box containing AgNPs, as confirmed by SEM-EDX analysis, was evaluated using food simulant solutions [i.e., water, 3% (v/v) acetic acid, and 10% and 90% (v/v) ethanol]. Silver release was investigated at temperatures in the 20-70 °C range using contact times of up to 10 days. Migration of silver from the food box was in all cases 2 to 3 orders of magnitude higher than that observed for the baby bottle, although the total silver content in the original box material was half of that found in the baby bottle. As expected, for both food containers, silver migration depended on both the nature of the tested solution and the applied conditions. The highest release was observed for 3% acetic acid at 70 °C for 2 h, corresponding to 62 ng dm2 and 1887 ng dm-2 of silver for the baby bottle and the food box, respectively. Single particle-inductively coupled plasma mass spectrometry (SP-ICPMS) was used to characterise and quantify AgNPs in the food simulants extracts. Sample preparation was optimized to preserve AgNPs integrity. The experimental parameters affecting AgNPs detection, sizing and quantification by SP-ICPMS were also optimised. Analyses of water and acidic extracts revealed the presence of both dissolved silver and AgNPs. Small AgNPs (in the 18-30 nm range) and particle number concentrations within the 4-1510 106 L-1 range were detected, corresponding to only 0.1-8.6% of the total silver released from these materials. The only exception was AgNPs migrated into water at 40 °C and 70 °C from the food box, which accounted for as much as 34% and 69% of the total silver content, respectively. © 2016 Elsevier B.V. All rights reserved. Source

Quintana M.C.,Autonomous University of Madrid | Ramos J.J.,IQOG | Hernandez L.,Autonomous University of Madrid | Ramos L.,IQOG
Journal of Liquid Chromatography and Related Technologies | Year: 2010

A simple and fast method for the determination of phenothiazines in bovine liver has been developed. The analytes were isolated from other liver components by a matrix solid phase dispersion (MSPD) procedure involving a mixture of C18 and sea sand as dispersants, a preliminary acidic digestion of the matrix and using acetonitrile as extraction solvent. Because of the complexity of the studied matrix, an extra cleanup of the collected extracts on neutral alumina was required before instrumental determination of the target compounds by high performance liquid chromatography with a fluorescence detector (HPLC-F). The optimised procedure, which involved only 0.250g of freeze dried sample and a total solvent consumption of 11mL, allowed accurate determination of the test compounds (recoveries 59-84% and RSD lower than 12% at a spiking level of 200ng/g wet sample), and limits of detection below 100ng/g (as calculated for real samples) for all test compounds. Source

Pena-Abaurrea M.,IQOG | Ramos J.J.,IQOG | Gonzalez M.J.,IQOG | Ramos L.,IQOG
Journal of Chromatography A | Year: 2013

A new miniaturized pressurized liquid extraction (PLE) with in-cell purification method has been developed for the simultaneous extraction of endogenous prioritary and toxic polychlorinated biphenyls (PCBs) and environmentally relevant tri- to deca-brominated diphenyl ether (PBDE) congeners from different feed matrices. Parameters affecting the efficiency of the selective PLE process, such as sorbent:matrix ratio, volume and nature of the extraction solvent, PLE working mode, extraction time and temperature, and amount of co-sorbents, were optimized. n-Hexane and n-hexane:dichloromethane (1:1, v/v) were used as extraction solvents. 8-mL of organic solvents and 3.5. g of sorbents sufficed for complete sample treatment. Only 0.25. g of feed sample were required for accurate determination of the endogenous PCBs studied using gas chromatography with a micro-electron capture detector (GC-μECD) during method development, and for PBDE analysis using either GC-μECD or gas chromatography with negative chemical ionization-quadrupole mass spectrometry (GC-NCI-qMS). Gas chromatography coupled to ion trap detection working in tandem mode, GC-ITD (MS/MS), was used for final PCB confirmation. Additional purification of the sample extracts was not required. The performance of the complete PLE-based method was evaluated at two spiking levels, 0.4 and 4. ng/g wet weight. Recoveries in the range 60-120% were obtained for PCBs, while those of PBDEs ranged from 86% to 114% for most of the target analytes. The relative standard deviations were in general lower than 20%. The optimized procedure was applied to the determination of the investigated PCBs and PBDEs in a variety of feed samples. © 2012 Elsevier B.V. Source

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