The determination of O,S,S-trimethylphosphorodithioate in the plasma and various tissues of rats using high-resolution gas chromatography with nitrogen-phosphorus detection.

A method has been developed for the determination of O,S,S-trimethylphosphorodithioate in the plasma, lung, liver, brain and thymus of rats using high-resolution gas chromatography. The organophosphorus compound was extracted from the biological sample with ethyl acetate and analysed on a carbowax 20M fused-silica capillary column with a nitrogen-phosphorus specific detector. O,S,S-Triethylphosphorodithioate was used as an internal standard added to the sample before extraction. The sensitivity of the method allowed the compound to be measured in 0.1-ml aliquots of plasma or in 20-mg wet weight of tissue down to a level of 5 ng/sample. The method has been applied to a pharmacokinetic study in the rat after an oral or intravenous dosage with 25 mg/kg of O,S,S-trimethylphosphorodithioate.