DETERMINATION OF REDUCED GLUTATHIONE IN HUMAN PLASMA USING LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION WITH A GLASSY-CARBON ELECTRODE CHEMICALLY-MODIFIED WITH INDIUM FERRICYANIDE

A stable indium ferricyanide-modified glassy carbon electrode (InHCF/GCE-2) was prepared and exhibited excellent electrocatalytic activity in the oxidation of reduced glutathione (GSH) in acidic media. Liquid chromatography with electrochemical detection (LCEC), incorporating the InHCF/GCE-2, has been employed for the determination of normal circulating levels of GSH in human plasma. The mobile phase consisted of 0.1 mol/liter phosphate butler (pH 3.0) containing 50 μmol/liter ethylenediaminetetraacetic acid (EDTA). A linear range was over two orders of magnitude. The limit of detection for GSH was 1.6 μmol/liter. The mean recovery of GSH added to the plasma was 98.7%. This was achieved following a simple sample pretreatment method, prior to LCEC, involving chelation of divalent cations with EDTA and subsequent acidification with orthophosphoric acid, using the LCEC method. The circulating level of GSH in plasma, found in three normal subjects, was 14-15 μmol/liter, which is in agreement with previously reported values. © 1994 Academic Press. All rights reserved.