Analysis of the cyanide metabolite 2-aminothiazoline-4-carboxylic acid in urine by high-performance liquid chromatography.

The cyanide metabolite 2-aminothiazoline-4-carboxylic acid (ATC) was converted to N-carbamylcysteine and analyzed by high-performance liquid chromatography (HPLC) and fluorometric detection. ATC was first separated from interfering substances by passing through the cation exchanger AG 50W-X8. Interfering disulfides were converted to thiols by reduction of the eluate with thiopropyl-Sepharose 6B. The thiols were then absorbed to the organomercurial absorbent p-acetoxymercurianiline-Sepharose 4B while ATC was obtained in the effluent. ATC was then converted to N-carbamylcysteine by ring opening at high temperature in an alkaline environment. Derivatization of N-carbamylcysteine was with N-(7-dimethylamino-4-methyl-3-coumarinyl)maleimide. The imprecision (CV) of the method was 3.6% and the analytical recovery was quantitative. The detection limit was 0.3 microM. ATC in urine was stable for at least 3 months when stored at -196 to +20 degrees C. The ATC concentration in urine was below the limit of detection in health nonsmokers. The utility of the method was demonstrated by the finding of up to 10.5 microM ATC concentrations in urine samples from human subjects in Mozambique living on a high dietary intake of cyanide from the cassava root. In a metabolic study rats were exposed to acetonitrile in the drinking water. After 4 weeks very high ATC levels were found in the urine, representative values from two rats being 195 and 525 microM, respectively.