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Multiresidue analysis of 102 organophosphorus pesticides in produce at parts-per-billion levels using a modified QuEChERS method and gas chromatography with pulsed flame photometric detection

Schenck, F.; Wong, J.; Lu, C.; Li, J.; Holcomb, J.R.; Mitchell, L.M.

Journal of Aoac International 92(2): 561-573

2009


ISSN/ISBN: 1060-3271
PMID: 19485217
DOI: 10.1093/jaoac/92.2.561
Accession: 054504659

A multiresidue method for the analysis of organophosphorus pesticides in fresh produce at levels down to 1.0 microg/kg (ppb) has been developed using a modification of the QuEChERS (quick, easy, cheap, effective, rugged, and safe) procedure. The procedure entails extraction of pesticides from the sample with acetonitrile, salting-out with magnesium sulfate (MgSO4) and sodium chloride, and cleanup of the resulting extracts with dispersive solid-phase extraction using primary-secondary amine, graphitized carbon black, and MgSO4. Fortification studies were performed for 102 organophosphorus pesticides at 1.0, 10, and 100 ppb in 4 different pesticide-free commodities (grape, orange, spinach, and tomato). Recoveries ranged from 63-125%, with >80% being achieved for most of the pesticides tested in each commodity. The procedure was applied to the analysis of 400 produce samples collected from a cohort of children that participated in the Children's Pesticide Exposure Study and the Longitudinal Dietary Pesticide Exposure Study in which selected 24 h duplicate food items were collected throughout a 12-month period. Residues of 15 of the 102 pesticides were detected at levels ranging from <1 to 526 ppb.

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