Acidic metabolites of pseudocumene in rabbit urine.

In order to identify biological indicators of exposure to trimethylbenzenes, the metabolism of pseudocumene (1,2,4-trimethylbenzene) was investigated in rabbits. After oral administration of this compound, urine was collected for several days and analyzed for the presence of acidic metabolites. Isolation techniques included steam-distillation, direct extraction of urine by ethyl acetate, preparative thin-layer and column chromatography of the extract. The metabolites were identified by microanalysis, followed by TLC, gas chromatography-mass spectrometry, infrared and ultraviolet spectroscopy. Two major urinary metabolites were identified namely 2,4-dimethylbenzoic acid and 3,4-dimethylhippuric acid. The presence of these acidic metabolites in urine is a good indication of exposure to pseudocumene.