Sensitive gas chromatographic method for determination of mercapturic acids in human urine

A method was developed for sensitive determination of the specific benzene metabolite S-phenylmercapturic acid and the corresponding toluene metabolite S-benzylmercapturic acid in human urine for non-occupational and occupational exposure. The sample preparation procedure consists of liquid extraction of urine samples followed by precolumn derivatization and a clean-up by normal-phase HPLC. Determination of analytes occurs by gas chromatography with electron-capture detection. With this highly sensitive method (detection limits 60 and 65 ng/l, respectively) urinary S-phenylmercapturic and S-benzylmercapturic acid concentrations for non-occupationally exposed persons (e.g. non-smokers) can be measured precisely in one chromatographic run. Validation of the method occurred by comparison with a HPLC method we have published recently.