Detection of S-methylfenitrothion, aminofenitrothion, aminofenitroxon and acetylaminofenitroxon in the urine of a fenitrothion intoxication case

A 23-year-old male attempted suicide by ingesting approximately 50 ml of 5% fenitrothion emulsion, and vomited soon afterwards. He was admitted to a hospital about 3 h after ingestion. He recovered and was discharged from hospital 3 days after admission. The serum cholinesterase activity (normal range: 175-440 I.U.) was only 29 at 3 h, 32 at 1 day, 59 at 2 days and 75 at 3 days after ingestion. Fenitrothion and its metabolites in the body fluids were extracted by an Extrelut column extraction method, detected by a gas chromatograph equipped with either a hydrogen flame ionization detector or a flame photometric detector, and confirmed by a gas chromatograph-mass spectrometer. Fenitrothion concentration in the blood was 169.5 ng/g at 3 h after ingestion. The half life of blood fenitrothion concentration was found to be about 4.5 h. Fenitrothion metabolites, 3-methyl-4-nitrophenol, aminofenitrothion, aminofenitroxon, acetylaminofenitroxon and S-methylfenitrothion, were detected in the urine samples. All of them except S-methylfenitrothion were detected in the urine samples collected up to 62 h after ingestion. It would appear therefore that fenitrothion poisoning can be determined by detection and analysis of the metabolites in urine even if fenitrothion has not been detected in the blood.