Quantitative determination of urinary hippuric acid and m- or p-Methylhippuric Acid as Indices of toluene and m- or p-Xylene exposure by high performance liquid chromatography

Summary A high performance liquid chromatographic method for the determination of hippuric and m-(p-)methylhippuric acids in urine, metabolites of toluene and m-(p-)xylene, is described. A stainless-steel column packed with octadecyl silanized silica gel was used and the mobile phase was a mixed solution of methanol/water/acetic acid (20/80/0.2). The method is simple and specific. Urine can be analyzed directly, without solvent extraction or pretreatment. The method has a lower detection limit of 0.2 g on column. All the analysis and quantitative determination can be performed within about 30 min. for samples containing m-(p-)methylhippuric acid.