COMPLEMENTATION OF GC-AED AND ELISA FOR THE DETERMINATION OF DIAZINONAND CHLORPYRIFOS IN FRUITS AND VEGETABLES

Enzyme-linked immunosorbent assay (ELISA) was employed to screen produ ce samples for diazinon and chlorpyrifos levels. All positive samples were analyzed for these organophosphate insecticides with a newly deve loped gas chromatographic atomic emission detection (GC-AED) method. P roduce was extracted in methanol by Polytron homogenization and cleane d up and concentrated using Sep-Pak C-18 cartridges. Fortification and reproducibility studies were performed using apples, blueberries, gre en beans, lettuce, and tomatoes that were foe of detectable levels dia zinon and chlorpyrifos. Percent coefficient of variation (%CV) from th e reproducibility studies ranged from 1.9 to 17 for chlorpyrifos and 1 .9 toll for diazinon. Spiking studies demonstrated percent recoveries of 78 to 114% (%CV 3.1 to 13%) for diazinon and 82 to 123 (%CV 1.5 to 12) for chlorpyrifos. Of the 278 fruit and vegetable samples screened for both organophosphate insecticides, 59 were found to have delectabl e levels of diazinon and 35 samples were found to contain delectable a mounts of chlorpyrifos. A correlation study between ELISA and GC-AED d emonstrated that the correlation coefficient was 0.987 for diazinon an d 0.967 for chlorpyrifos.