Simultaneous determination of the urinary metabolites of toluene, xylene and styrene using high-performance capillary electrophoresis. Comparison with high-performance liquid chromatography.

A simple and rapid method using high-performance capillary electrophoresis (HPCE) for the simultaneous determination of the urinary metabolites of toluene, xylene and styrene, plus creatinine and uric acid in human urine specimens and standard solutions is described. The compounds were well separated from each other on a fused-silica capillary utilizing a 20 mM sodium tetraborate buffer (pH 9.65) with 15 mM beta-cyclodextrin and UV detection at 200 and 225 nm. The total analysis time was less than 6 min per sample. The capillary zone electrophoresis (CZE) method shows a good correlation with the high-performance liquid chromatography (HPLC) method with respect to urinary hippuric acid concentrations in the urine specimens of subjects exposed to the vapors of a solvent mixture of toluene and xylene. In comparing these two techniques, HPCE was found to be superior to HPLC because the analysis time is shorter, and the separation of m-MHA and p-MHA takes a long time with HPLC.