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.

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The determination of cobalt by electrothermal atomic absorption spectrometry with a tungsten tube atomizer has been investigated. The absolute characteristic mass (the mass of element giving 0.0044 abs.) of cobalt by the atomizer was 5.8 pg and the detection limit was 0.65 ng/ml (3S/N). The interferences caused by large amounts of interferents like Al, Ca, Cu, Fe, K, Mg, Na, Pb and Zn were evaluated and most of these elements were found to interfere with the cobalt signal. Ammonium thiocyanate as a chemical modi®er was found to be ef®cient to eliminate the severest interferences. The accuracies of the recommended method were found to be almost satisfactory for the determination of cobalt in biological materials, as shown by a comparison with the reported values of NIST materials at the 0.02±0.4 mg/g level.