Determination of 2-carboxy thiazolidine-4-carboxylic acid in biological fluids by ion-exchange chromatography.

A column ion-exchange chromatographic method for the determination of 2-carboxy thiazolidine-4-carboxylic acid (TDCA) in blood and urine is described. After elimination of endogenous thiols, alkaline hydrolysis of the compound yields cysteine which is determined spectrophotometrically. The described method is specific for intact TDCA. Using a 3-ml aliquot of sample it allows the linear determination of this hepatoprotective drug from 5 micrograms TDCA ml-1 with a detection limit of 3 micrograms ml-1. The method was applied to study the time course of plasma levels and urinary excretion. An in vitro metabolism study showed that TDCA has a potential as a cysteine donor for glutathione synthesis.