Chromatographic assays for traces of potentially carcinogenic metabolites of two azo dyes, Direct Red 2 and Direct Blue 15, in rat, hamster and human urine.

Specific, precise and sensitive methods are described for determining traces of potentially carcinogenic metabolites of Direct Red 2 and Direct Blue 15 in rat and hamster urine and to monitor the urine from workers who may be occupationally exposed to these dyes. This methodology is generally applicable to metabolites of azo dyes based on benzidine or three of its congeners. The benzidine-congener free amines, their mono and diacetylated analogs and alkaline hydrolyzable conjugates were determined after appropriate extraction and hydrolysis by HPLC or EC/GC. Residues of metabolites in rat, hamster, and human urine were determined at levels as low as 1 ppb. Supplementary information is also presented concerning hydrolysis of diacetylated metabolites and the stability of Direct Red 2 and Direct Blue 15 in rat, hamster and human urine.