Urinary metabolites of sarin in a patient of the Matsumoto sarin incident

Abstract

Sarin metabolites were measured in urine from a patient with sarin poisoning. Two metabolites, methylphosphonic acid (MPA) and isopropylmethylphosphonic acid (iPMPA), were detected by gas chromatography after conversion to volatile derivatives with N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide in the urine from the victim collected on the first day of hospitalization. iPMPA was detected in the urine on the seventh day, but MPA could not be detected in the urine sample. MPA was narrowly detected in the urine collected on the third day. The concentration of iPMPA was estimated on the assumption that the sensitivity of phosphorus was the same as that of MPA. The total excretion of iPMPA and MPA in the urine was 2.1 mg and 0.45 mg, respectively. When all the sarin inhaled was excreted within a week as these two metabolites, the subject was considered to have been exposed to 2.79 mg (0.05 mg/kg) sarin at the incident. Thus, the measurement of sarin metabolites in urine is a useful tool for the biological monitoring of exposure to sarin.