trans,trans-Muconic acid, an open-chain urinary metabolite of benzene in mice. Quantification by high-pressure liquid chromatography.

A sensitive h.p.l.c. method is described which separated urinary metabolites from benzene-treated male CD-1 mice. Phenol, trans,trans-muconic acid and quinol in the 48 h urine accounted, respectively, for 12.8-22.8, 1.8-4.7 and 1.5-3.7% of the orally administered single dose of benzene (880, 440 and 220 mg/kg body wt.). Catechol occurred in trace amounts. Ascorbic acid was used to adjust urine pH and increase the extraction efficiency of metabolites, especially muconic acid. It allowed an accurate estimation of quinol by preventing its auto-oxidation. trans,trans-Muconic acid was identified and was unique to benzene as none was detected in urine of mice dosed orally with phenol, catechol or quinol (250, 150 and 200 mg/kg, respectively). The potential existence of a toxic benzene metabolite in the form of an aldehyde precursor of muconic acid in vivo is discussed.