Multiresidue determination of pesticides in fruit and vegetables by gas chromatography/tandem mass spectrometry

Pesticide residues in fruit and vegetables were determined by gas chromatog raphy/tandem mass spectrometry (GC/MS/MS). Electron impact (EI)/MS/MS and c hemical ionization (Cl)/MS/MS were developed for 80 compounds, including or ganochlorine, organophosphorus, organonitrogen, and pyrethroids, providing unambiguous spectral confirmation for these complex matrixes. Residues were extracted from samples with acetone followed by a mixture of dichlorometha ne-petroleum ether. Two injections per sample were required for analysis of the entire pesticide list by EI/MS/MS and CI/MS/MS. Initial steps involvin g cleanup and concentration of extracts were eliminated. The excellent sele ctivity and good linearity allowed quantification and identification of low levels of pesticides in the most difficult matrixes. The method has been u sed for routine analysis of many vegetables.