High-performance liquid chromatographic studies of toluene and xylene poisoning Part I: Workers' exposure to toluene and xylenes estimated from metabolites in their urine in a shipyard

In this paper, the author describes the determination of metabolites in the urine of shipyard workers exposed to thinner containing toluene and xylenes. Urine was taken from 4 healthy workers working at the same place, in the morning (a.m. 8:00), at noon (p.m. 0:00) and in the afternoon (p.m. 5:00), 3 times in a day for 5 consecutive days. Urinary metabolites, i.e., m-methylhippuric acid, p-methylhippuric acid and hippuric acid, were determined by high-performance liquid chromatography. The results were: 1. m-Methylhippuric acid, p-methylhippuric acid and hippuric acid in the urine of painting workers could be determined by high-performance liquid chromatography following extraction and benzoxylation. The stationary phase used in this experiment was silica gel and the mobile phase was a mixture of n-hexane and chloroform. 2. Concentrations of urinary m- and p-methylhippuric acids and hippuric acid were lowest just before, and generally highest just after, work. These results suggest that the workers were inhaling the thinner vapor even though wearing gas masks. 3. Peaks of m- and p-methylhippuric acids occurred in the chromatogram of workers' urine collected before work in the morning, although there were no peaks in the chromatogram of normal urine. This indicates that m- and p-xylenes may still remain in the workers' bodies