Simultaneous determination of urinary metabolites of toluene, xylene, styrene and ethyl benzene by solid-phase extraction technique and high-performance liquid chromatographic/photo diode array detection

To determine the level of urinary hippuric acid, methylhippuric acid, mandelic acid, and phenylglyoxylic acid, a method by solid-phase extraction (SPE) pretreatment and reversed-phase high performance liquid chromatography with photo diode array detection has been developed in this study. Six milliliter of methanol is the only solvent used in the SPE procedures. After extraction, the urine sample is injected onto a 5 μm RP18-LiChrospher 100 column (150 mm × 4 mm I.D.). The mobile phase is a mixture of acetonitrile (15 parts) and phosphate buffer (85 parts) containing tetrabutyl ammonium hydrogen sulfate (8.5 mM). The entire procedure is performed in 40 min. The method is simple, rapid and highly specific, and applicable in field study of toluene, xylene, styrene and ethyl benzene exposure.