Quantitation of homocysteine in human plasma by capillary electrophoresis and laser-induced fluorescence detection

Abstract

Homocysteine (Hcy) represents a branching point between the transsulfuration and transmethylation pathway of methionine. A large increase of plasma concentration of Hcy is observed in patients with inherited hyperhomocysteinemia. A moderated increase (above 10 μ M) is also observed in various pathological conditions, such as arterial occlusion, hypertension, hyperlipidemia and chronic renal failure. While amino acids were largely studied using capillary electrophoresis with UV or laser-induced fluorescence detection (LIF), thiol-amino acids were not. In this work we present a new approach for testing homocysteine in human plasma using CE–LIF and fluorescein isothiocyanate. The low fluorescence yield of the fluorescein thiocarbamyl (FTC) thiol-amino acids limits, probably, the sensitivity of the detection to 8·10 −10 M (instead of 10 −12 M for FTC–arginine).