Synthesis of 2-thiothiazolidine-4-carboxylic acid and its chromatography in rat and human urine.

2-Thiothiazolidine-4-carboxylic acid (TTCA), the urinary biological monitoring marker for carbon disulfide in humans was synthesized by reacting carbon disulfide with L-cystine. Validation of TTCA purity required elemental as well as mass spectral and chromatographic analyses. Two reversed-phase high-performance liquid chromatographic columns in series were necessary to resolve picomole amounts of TTCA from rat and human urine background peaks on detection at 272 nm even after prior diethyl ether extraction from acidified urines in the presence of saturated sodium chloride. The isolation procedure for TTCA from urine had a recovery of 94.0 +/- 8.1% in the linear 1.1-330 microM concentration range (0.0165-4.95 nmol injected mass) with a coefficient of variation of 8.6%. The detection limit was about 100 nM (1.5 pmol injected mass).