Biological conversion of benzaldehyde to benzylmercapturic acid in the Sprague-Dawley rat

The metabolism of benzaldehyde was investigated in Sprague-Dawley rats. After repeated oral administration of this compound (0.4-1.0 g/kg) for 13 consecutive days, urine was collected and analyzed for the presence of metabolites. The acidification of the pooled urine samples (pH:2.0) with 6 N H2SO4 was followed by ethyl acetate extraction, evaporation of the extract and methylation with diazomethane. Identification of the metabolite by comparison with a synthetic sample of benzylmercapturic acid (BENZM) was conducted by gas chromatography. Mass spectrometry examination of this metabolite revealed the following peaks characteristic of benzylmercapturic acid: m/z (%), 91(100), 176(27), 208(23), 43(20), 88(13), 117(10), 134(9), M+ 267(2). Monitoring of urines from both female and male rats showed a dose-related increase of benzylmercapturic acid which was found to be a reliable indicator of exposure to benzaldehyde.