Analysis of homocysteine and thiol-containing compounds using the heterocyclic disulfides

Biological low-molecular aminothiols, such as homocysteine, are characterized by the weak absorption in the UV – visible range. Therefore, aminothiols analysis requires using thiol-specific chemosensors or derivatization procedure. Heterocyclic disulfides belong to a large group of derivatizing agents. However, the disulfides widely used in the analytical practice, such as 5,5'-dithiobis-(2-nitrobenzoic acid), have several disadvantages: limited acceptable pH range, low sensitivity, susceptibility to hydrolisys. Hence, the search for the effective derivatizing agents continues. In the current work, 2,2'-dithiobis[benzoxazole] and 8,8'-dithiobis-quinoline disulfides were used for the analysis of homocysteine. Precise and sensitive methods (homocysteine detection limit in the range of 1.1·10-6–7.8·10-6 M, relative standard deviation in the range of 1.5–4.6%) for the homocysteine determination have been developed, including spectrophotometric method, capillary electrophoresis (CE), high-performance liquid chromatography (HPLC) and kinetic method with the spectrophotometric detection. The proposed disulfides have also been successfully used in the analysis of sulfhydryl groups content in the sample of human urine.