Quantitation of urinary o-xylene metabolites of rats and human beings by high performance liquid chromatography

Summary A high performance liquid chromatographic method for the determination of urinary o-xylene metabolites of rats, volunteers, and workers was described. In rat urine, the major metabolite, indicated by the glucuronic acid reaction, was separated with thin-layer liquid chromatography and identified as o-toluic acid glucuronide by high performance liquid chromatography. Another rather minor metabolite was demonstrated to be o-methyl hippuric acid. One of the major urinary metabolite in volunteers administered o-xylene orally was demonstrated to be o-methylhippuric acid and another minor metabolite was o-toluic acid glucuronide. In the urine of volunteers exposed to 138 ppm of o-xylene for 3 h in an artificial exposure chamber, o-methylhippuric acid was found to be the major metabolite and a minute amount of o-toluic acid glucuronide was found to be the minor metabolite. In the urine of shipbuilding workers, using a thinner containing toluene and xylenes (o-, m- and p-), hippuric acid and methylhippuric acids (o-, m- and p-) were recognized. Thus, urinary o-methylhippuric acid could be an index of o-xylene exposure of workers.