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Geis-Asteggiante L.,U.S. Department of Agriculture | Lehotay S.J.,U.S. Department of Agriculture | Heinzen H.,Catedra de Farmacognosia y Productos Naturales
Journal of AOAC International | Year: 2012

Despite its many documented advantages, the QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) sample preparation approach has problems with a few unstable pesticides, partly due to the exothermic reaction generated by the use of anhydrous magnesium sulfate (anh. MgSO4) during extraction. These pesticides also tend to be difficult to analyze by GC/MS. The aim of this study was to evaluate the effect of temperature during the extraction process in a revised version of AOAC Official MethodSM 2007.01 using anh. MgSO4 ≥99% (fine powder) or ≥97% (granular) purity, and the use of an ice bath for particular unstable pesticides of interest (chlorothalonil, captan, captafol, folpet, and the degradation products cis-1,2,3,6- tetrahydrophthalimide and phthalimide). Recoveries of 38 representative pesticides were measured in limes and broccoli at different extraction conditions by LC/MS/MS and low-pressure GC/MS/MS. Results showed that the difference in temperature when using ≥99% versus ≥97% purity anh. MgSO4 was 6-9°C, which did not lead to significant differences in recoveries. The use of an ice bath aided recovery for some of the analytes in broccoli, but no significant differences were observed for limes, which already provided greater stability of the basesensitive analytes due to acidity of the matrix.

Boido E.,Seccion Enologia | Garcia-Marino M.,University of Salamanca | Dellacassa E.,Catedra de Farmacognosia y Productos Naturales | Carrau F.,Seccion Enologia | And 2 more authors.
Australian Journal of Grape and Wine Research | Year: 2011

Background and Aims: Changes in different polyphenol families during grape ripening and vinification were determined in Tannat grapes. This was done to establish a polyphenol profile for Tannat grapes during ripening and for young wines. Methods and Results: We demonstrated, by high-performance liquid chromatography with diode array detection and mass spectrometry (HPLC-DAD-MS) analysis, that the content of flavan-3-ols in Tannat seeds was higher than that reported for a large number of other grape varieties analysed. Forty percent of the total flavan-3-ols in seeds were galloylated compounds, whereas the flavan-3-ol profile in skins was characterised by the absence of galloylated forms. Prodelphinidins in skins ranged between 30 and 35% with very low values for epigallocatechin. Epicatechin gallate was not detected in Tannat wine and galloylated forms represented a low percentage of total flavan-3-ols. Tannat grapes had very high concentrations of anthocyanins in skins with levels increasing during ripening. Eleven phenolic acids were identified in Tannat grape skins and wines, but only gallic and protocatechuic acids were found in the seeds. Conclusions: Tannat wines were shown to have one of the highest levels of phenolic compounds reported for vinifera grape varieties. The profiles for different polyphenol families present in Tannat grapes (skins and seeds) and wines were determined. Significance of the Study: The results presented will help to better understand the phenolic winemaking potential of this variety and its functional properties within food chemistry. © 2011 Australian Society of Viticulture and Oenology Inc.

Geis-Asteggiante L.,U.S. Department of Agriculture | Lehotay S.J.,U.S. Department of Agriculture | Fortis L.L.,U.S. Department of Agriculture | Paoli G.,U.S. Department of Agriculture | And 2 more authors.
Analytical and Bioanalytical Chemistry | Year: 2011

Microcystins (MCs) are the most common cyanotoxins found worldwide in freshwater, brackish, and marine environments. The rapid and accurate analysis of MCs and nodularin (Nod-R) in fish tissue is important for determining occurrence, following trends, and monitoring exposure for risk assessment and other purposes. The aim of this study was to develop a streamlined and reliable sample preparation method for eight MCs (MC-RR, MC-YR, MC-LR, MC-WR, MC-LA, MC-LY, MC-LW, and MC-LF) and Nod-R in fish, and conduct a validation of the new method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for analysis and compare the results with a commercial enzyme-linked immunosorbent assay (ELISA) kit. Different sample preparation methods were compared, and a simple extraction protocol with acidified acetonitrile/water (3:1) followed by hexane partitioning cleanup was found to be most effective. Thorough validation of the final method was conducted, and 90-115% recoveries were achieved for all analytes except for MC-RR, which gave 130% average recovery (isotopically labeled internal standards were unavailable to correct for possible biases). The use of electrospray ionization in the negative mode gave few interferences and minimal matrix effects in the LC-MS/MS analysis overall. Precision was typically 10-20% RSD among multiple days in experiments, detection limits were <10 ng/g in the fish tissue (catfish, basa, and swai filets), and no false-positives or false-negatives occurred in blind analyses of many spiked samples. The ELISA was unable to distinguish between MCs but was found to correctly assess the presence or absence of MCs and Nod-R in the blind-fortified fish tissues. The capability of these approaches to measure covalently bound MCs was not assessed. © 2011 Springer-Verlag (outside the USA).

Pareja L.,Catedra de Farmacognosia y Productos Naturales | Colazzo M.,Catedra de Farmacognosia y Productos Naturales | Perez-Parada A.,Catedra de Farmacognosia y Productos Naturales | Niell S.,Catedra de Farmacognosia y Productos Naturales | And 5 more authors.
International Journal of Environmental Research and Public Health | Year: 2011

The influence of insecticides commonly used for agricultural purposes on beehive depopulation in Uruguay was investigated. Honeycombs, bees, honey and propolis from depopulated hives were analyzed for pesticide residues, whereas from active beehives only honey and propolis were evaluated. A total of 37 samples were analyzed, representing 14,800 beehives. In depopulated beehives only imidacloprid and fipronil were detected and in active beehives endosulfan, coumaphos, cypermethrin, ethion and chlorpyrifos were found. Coumaphos was present in the highest concentrations, around 1,000 μg/kg, in all the propolis samples from active beehives. Regarding depopulated beehives, the mean levels of imidacloprid found in honeycomb (377 μg/kg, Standard Deviation: 118) and propolis (60 μg/kg, Standard Deviation: 57) are higher than those described to produce bee disorientation and fipronil levels detected in bees (150 and 170 μg/kg) are toxic per se. The other insecticides found can affect the global fitness of the bees causing weakness and a decrease in their overall productivity. These preliminary results suggest that bees exposed to pesticides or its residues can lead them in different ways to the beehive. © 2011 by the authors.

Pareja L.,University of Almeria | Pareja L.,Centro Universitario Of Paysandu | Perez-Parada A.,University of Almeria | Aguera A.,University of Almeria | And 4 more authors.
Chemosphere | Year: 2012

Quinclorac (QNC) is an effective but rather persistent herbicide commonly used in rice production. This herbicide presents a mean persistence in the environment so its residues are considered of environmental relevance. However, few studies have been conducted to investigate its environmental behavior and degradation. In the present work, direct photolysis and TiO 2 photocatalysis of the target compound in ultrapure and paddy field water were investigated. After 10h photolysis in ultrapure water, the concentration of QNC declined 26% and 54% at 250 and 700Wm -2, respectively. However, the amount of quinclorac in paddy field water remained almost constant under the same irradiation conditions. QNC dissipated completely after 40min of TiO 2 photocatalysis in ultrapure water, whereas 130min were necessary to degrade 98% of the initial concentration in paddy field water. Possible QNC photolytic and photocatalytic degradation pathways are proposed after structure elucidation of the main transformation products, through liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry and exact mass measurements. Pyridine ring hydroxylation at C-9 followed by ring opening and/or oxidative dechlorination were the key steps of QNC degradation. © 2012 Elsevier Ltd.

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