Simultaneous determination of pesticides in agricultural products by solid-phase extraction and gas chromatography mass spectrometry

A method was developed for determining 107 pesticides in agricultural products. Residues were extracted from samples with acetonitrile, and coextractives were removed with both ODS and PSA mini-column cleanup. Analysis was performed by gas chromatography with mass spectrometry. Positive analytes were confirmed on the basis of retention time and relative response ratio of two fragment ions. A limit of detection of 0.01 ppm was available for all compounds with two injections per sample for both scan and selected ion monitoring mode analyses. Recovery data were obtained by fortifying 3 matrices (brown rice, lemon, and spinach) at 0.1 ppm. Recoveries were more than 50% except for 6 pesticides, whose recoveries varied among the different matrices. The method demonstrated acceptable performance for screening analysis (including polar compounds). The method was applied to 157 samples. From 69 samples, 34 pesticides were detected at levels of more than 0.01 ppm. No sample was contaminated to a level that would contravene the Food Sanitation Law in Japan.