The screening of organophosphorus, organochlorine and synthetic pyrethroid pesticides residues in beef fat by tandem solid-phase extraction technique

For regulatory monitoring of pesticides in environmental matrices, a multiresidue analysis through solid phase extraction (SPE) technique and using gas chromatographic determination of organochlorine(OC), organophosphorus(OP) and synthetic pyrethroid pesticides residues in beef fat was studied. The group of pesticides was added to dissolved beef fat (0.5 g) and blended with 8% de-activation florisil. The florisil/fat mixture was packed into disposable filtration columns. This column was tandem with an octadecyl SPE column and was eluted with acetonitrile. The pesticide residues were determined by gas chromatography with electron capture and flame photometric detectors. Three kinds (including OC, OP and synthetic pyrethroid) with a total of 71 pesticides (including their metabolites) were tested in this study. With the exception of isoxthion and flucythrinate with high recovery rates (122% +/- 13% and 137% +/- 31%, respectively), according to the correlation coefficients for the 71 extracted pesticide standard curves (ranging from 0.9915 +/- 0.0176 to 0.9999 +/- 0.0200, n = 5), average recovery rate (ranging from 68 +/- 9% to 117 +/- 11%, n = 25 for each insecticide), inter-assay variability (ranging from 3 +/- 3% to 17 +/- 12%, n = 25 for each insecticide), intra-assay variability(ranging from 3 to 19%, n = 5 for each insecticide) indicated that the methodology is acceptable for the extraction, determination, and screening of theses residues in beef fat. The detection limits for OCs, OPs and synthetic pyrethroid pesticides are 2similar to21 ng/g, 6similar to31 ng/g and 3similar to118 ng/g, respectively. Comparing with studies conducted by the National Analytical Reference Laboratory in Western Australia in the field of pesticide residue testing in beef fat, the results indicated that the present method could accurately measure commonly used pesticide chemicals.