Study on the determination of pesticide residues in crops by ion-trap GC/MS/MS

Ion-trap GC/MS/MS was evaluated for the multi-residue determination of pesticides in agricultural products. Matrices were extracted from samples (spinach, carrot, onion and brown rice) with acetone and submitted to gel permeation chromatography, followed by a clean-up step through a graphite carbon cartridge. Thirty-five pesticides were added to either matrix, and analyzed by GC/MS/ MS. Detection limits of pesticides by GC/MS/MS was almost the same as those by GC/MS (SIM). Coefficients of variation of peak area in 5 measurements of each pesticide at 0.1 mug/mL or 0.05 mug/ mL with or without matrices were mostly acceptable, though those of 20 pesticides out of 35 were higher than 10% at a concentration of 0.02 mug/mL. It was indicated that matrix artifacts, which interfere with GC/MS-Scan analysis, could be eliminated in some cases by using GC/MS/MS.