Urinary metabolites of organic solvents Report 1: Quantitative determination on urinary metabolites of toluene, xylene and styrene by thin-layer chromatography.

A simple and specific method for the quantitative determination of hippuric acid and methylhippuric acids is described. Urine samples were applied to silica gel plates (silica gel, 60 F254), and developed with chloroform- toluene-methanol-acetic acid (8:2:2:1). The spots of hippuric acid, m- or p-methylhippuric acids, o- methylhippuric acid, mandelic acid and phenylglyoxylic acid were identified by illuminating the silica gel plates with an ultraviolet lamp. The spots of hippuric acid, m- or p-methylhippuric acids and o-methylhippuric acid were scratched off and extracted with pyridine. The color was then developed with acetic anhydride and p-dimethylaminobezaldehyde (DAB) in pyridine at 40℃ for 60min. The absorbance at 458 nm was determined against a blank containing pyridine acetic anhydride and DAB