STUDIES ON SIMULTANEOUS DETERMINATION OF 12 PYRETHROID AND 29 ORGANOPHOSPHORUS PESTICIDES IN AGRICULTURAL PRODUCTS

A method of preparing a test solution for 29 organophosphorus and 12 pyrethroid pesticides from vegetables and fruits was systematically developed. It consists of extraction with acetone followed by clean-up with coagulating solution and, for cereals and beans, by extraction with acetonitrile followed by washing with hexane. Twenty-nine organophosphorus and 10 pyrethroid pesticides were simultaneously determined by FPD-GC and NPD-GC, respectively. Allethrin and permethrine were individually determined by GC/MS (SIM). Recovery tests for the pesticides spiked at 0.01 ppm for organophosphorus pesticides and 0.25 ppm for pyrethrine pesticides were satisfactory, and no interfering peaks were observed in the determination except in the case of onion in FPD-GC. Recoveries of the above-mentioned pesticides in tea leaves were compared between acetone extraction according to the proposed method and the official hot water steeping method. Almost all of the pesticides were recovered by the proposed method, but only a small part of the pesticides were recovered by the official method. Contents of residual pesticides in imported agricultural products (pumpkin, onion, orange, lemon, wheat, soybean, tea) were determined by the proposed method. Chlorpyrifos in lemon (175 ppb) and orange (83 ppb) from the U.S.A and fenvalerate in tea (157 ppb) from China were detected.