Estimation of N-hydroxy-o-toluidine, a urinary metabolite of o-toluidine and o-nitrosotoluene, by high performance liquid chromatography with electrochemical detection.

High-performance liquid chromatography with electrochemical detection, a highly sensitive and specific method, was used to determine N-hydroxy-o-toluidine and o-toluidine in the urines of male F344 rats after the administration of 0.82 mmol/kg of o-toluidine or o-nitrosotoluene. In a six hour period, 0.11% of the dose was excreted by o-toluidine-treated rats as N-hydroxy-o-toluidine and 3.61% as o-toluidine. In the same period, 0.48% of the dose was excreted by o-nitrosotoluene treated rats as N-hydroxy-o-toluidine and 0.38% as o-toluidine. The urinary excretion of the N-hydroxy-o-toluidine metabolite may play a role in the carcinogenicity of o-nitrosotoluene and o-toluidine toward the rat bladder.