LIQUID-CHROMATOGRAPHIC DETERMINATION OF URINARY 2-THIOTHIAZOLIDINE-4-CARBOXYLIC ACID, A BIOMARKER OF CARBON-DISULFIDE EXPOSURE

An effective gradient high-performance liquid chromatographic method f or baseline separation of urinary 2-thiothiazolidine-4-carboxylic acid (TTCA), with photodiode array detection at 271 nm was described. o-Me thylhippuric acid was used as an internal standard (I.S.). A 1-ml urin e sample was saturated with 300 mg of sodium sulphate, acidified with 100 mu l of 6 M hydrochloric acid, extracted twice with 2 ml of diethy l ether, and after evaporation, the residue was taken up in 1 ml of 0. 1% (v/v) phosphoric acid. The two mobile phases used for gradient elut ion were: (A) 10 mM ammonium dihydrogenphosphate (pH 3.5) and (B) same concentration of buffer but containing 20% (v/v) of methanol (pH 4.8) . The flow-rate was set at 1.0 ml/min. TTCA and I.S. were detected at 2.2 and 9.1 min, respectively. The method was validated with urine sam ples collected from normal subjects and workers occupationally exposed to carbon disulphide. The present method enables the detection of uri nary TTCA at a concentration of 0.025 mg/l. Analytical recovery and re producibility generally exceeded 90%. The proposed method is considere d more sensitive, specific and reliable than other existing methods.