High-performance liquid chromatography analysis of thiazolidine-4-carboxylic acids in human serum samples

In the presented paper we studied analytical characteristics of three thiazolidine-4-carboxylic acids. These compounds obtained by condensation of aldehydes with L-cysteine are interesting from the biological point of view. The proposed method involves a solid phase extraction (SPE) of thiazolidinic acids and their precursor aldehydes from human serum using C-18 SPE columns. Separation of the six analytes was achieved within 20 min using a reversed-phase HPLC SEPARON SGX C-18 column protected by precolumn, with mobile phase of methanol-water (phi(r) = 55 : 45) containing 5 cm(3) of acetic acid per 1 dm(3) of mobile phase (apparent pH 5.5). The recoveries of all studied compounds from the human serum were in the range of 86-89 %, the detection limits were 30 ng cm(-3) of serum.