High performance liquid chromatographic determination of mercapturic acids in urine of rats administered with m− or p-xylene

The determination of urinary mercapturic acid, N-acetyl-S-(m-xylyl)-L-cysteine or N-acetyl-S-(p-xylyl)-L-cysteine, was undertaken by HPLC after i.p. administration of m− or p-xylene to rats in order to confirm the structure of thioether which was known to be excreted in small amounts related with the metabolism of m− or p-xylene. The excretion rates of these mercapturic acids were much lower than those previously estimated from thioether determinations. The present study clearly demonstrates the mercapturic acid pathway operates only to limited degree as a metabolic route of m− or p-xylene.