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

Homocysteine (Hcy) represents a branching point between the transsulfuration and transmethylation pathway of methionine. A large increase of plasma concentration of Hey is observed in patients with inherited hyperhomocysteinemia. A moderated increase (above 10 mu 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-I,LF 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). (C) 1998 Elsevier Science B.V. All rights reserved.