492 research outputs found
Assessing Childrenâs Dietary Pesticide Exposure: Direct Measurement of Pesticide Residues in 24-Hr Duplicate Food Samples
Background: The data presented here are a response to calls for more direct measurements of pesticide residues in foods consumed by children and provide an opportunity to compare direct measures of pesticide residues in foods representing actual consumption with those reported by the U.S. Department of Agriculture Pesticide Data Program. Objective: We measured pesticide residues in 24-hr duplicate food samples collected from a group of 46 young children participating in the Childrenâs Pesticide Exposure Study (CPES). Methods: Parents were instructed to collect 24-hr duplicate food samples of all conventional fruits, vegetables, and fruit juices equal to the quantity consumed by their children, similarly prewashed/prepared, and from the same source or batch. Individual or composite food items were analyzed for organophosphate (OP) and pyrethroid insecticide residues. Results: We collected a total of 239 24-hr duplicate food samples collected from the 46 CPES children. We found 14% or 5% of those food samples contained at least one OP or pyrethroid insecticide, respectively. We measured a total of 11 OP insecticides, at levels ranging from 1 to 387 ng/g, and three pyrethroid insecticides, at levels ranging from 2 to 1,133 ng/g, in childrenâs food samples. We found that many of the food items consumed by the CPES children were also on the list of the most contaminated food commodities reported by the Environmental Working Group. Conclusions: The frequent consumption of food commodities with episodic presence of pesticide residues that are suspected to cause developmental and neurological effects in young children supports the need for further mitigation
Evaluation of the QuEChERS Method and Gas ChromatographyâMass Spectrometry for the Analysis Pesticide Residues in Water and Sediment
A method for the determination of pesticide residues in water and sediment was developed using the QuEChERS method followed by gas chromatography â mass spectrometry. The method was validated in terms of accuracy, specificity, linearity, detection and quantification limits. The recovery percentages obtained for the pesticides in water at different concentrations ranged from 63 to 116%, with relative standard deviations below 12%. The corresponding results from the sediment ranged from 48 to 115% with relative standard deviations below 16%. The limits of detection for the pesticides in water and sediment were below 0.003 mg Lâ1 and 0.02 mg kgâ1, respectively
Modification and re-validation of the ethyl acetate-based multi-residue method for pesticides in produce
The ethyl acetate-based multi-residue method for determination of pesticide residues in produce has been modified for gas chromatographic (GC) analysis by implementation of dispersive solid-phase extraction (using primaryâsecondary amine and graphitized carbon black) and large-volume (20Â ÎźL) injection. The same extract, before clean-up and after a change of solvent, was also analyzed by liquid chromatography with tandem mass spectrometry (LCâMSâMS). All aspects related to sample preparation were re-assessed with regard to ease and speed of the analysis. The principle of the extraction procedure (solvent, salt) was not changed, to avoid the possibility invalidating data acquired over past decades. The modifications were made with techniques currently commonly applied in routine laboratories, GCâMS and LCâMSâMS, in mind. The modified method enables processing (from homogenization until final extracts for both GC and LC) of 30 samples per eight hours per person. Limits of quantification (LOQs) of 0.01Â mg kgâ1 were achieved with both GCâMS (full-scan acquisition, 10Â mg matrix equivalent injected) and LCâMSâMS (2Â mg injected) for most of the pesticides. Validation data for 341 pesticides and degradation products are presented. A compilation of analytical quality-control data for pesticides routinely analyzed by GCâMS (135 compounds) and LCâMSâMS (136 compounds) in over 100 different matrices, obtained over a period of 15Â months, are also presented and discussed. At the 0.05Â mg kgâ1 level acceptable recoveries were obtained for 93% (GCâMS) and 92% (LCâMSâMS) of pesticideâmatrix combinations
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