In order to apply the multiresidue screening method to degradation products of N-trihalomethylthio fungicides (captan, captafol, folpet, dichlofluanid, tolylfluanid) and oxidized organophosphorus insecticides generated during sample preparation or in plants, the recovery of sixteen of these degradation products and metabolites from 3 agricultural products was investigated. The recoveries ranged from 74 to 129%, and these data suggest that the degradation products can be determined simultaneously with the parent pesticides by this method.
The degradation ratios of 5 N-trihalomethylthio fungicides, demeton-S-methyl and isofenphos were examined during sample preparation from 5 agricultural products and during GC injection. Cabbage, spinach and pumpkin readily caused the degradation of N-trihalomethylthio fungicides, and the degradation ratios of captan were 100, 100 and 81%, respectively. Decreases of the parent pesticides corresponded closely to the formation of the degradation products.