Abstract: This paper prerented a new method for idcntificating methamidophos in blood and its metabolite O、S－dimethylphosphate in urine by GC/SPD and GC/MS. Tributyl phosphate was used as interstandard for identificating metamidophos. The recovery of extracting methamidophos from rabbit blood was 75%. The detection limit was 10 ng/ml blood. The detection limit of determinating O、S-dimethylphosphate was 50 ng/ml urine.

Key words: methamidophos, O, S-dimethylphos phate, GC/SPD, GC/MS