Determination of reduced glutathione in human whole blood by high-performance liquid chromatography with electrochemical detection by a graphite-epoxy resin electrode chemically modified with cobalt phthalocyanine

High-performance liquid chromatography with electrochemical detection by means of a re-polishable graphite-epoxy resin composite electrode, modified with the electrocatalyst cobalt phthalocyanine, has been used for the determination of reduced glutathione (GSH) in 25-mul samples of whole blood. The mobile phase was O.O5M phosphate buffer (pH 2.3) containing 1 mM EDTA, used in conjunction with a Waters muBondapak ODS chromatography column. The use of the electrocatalyst reduced the overpotential for the oxidation of GSH at a carbon electrode by approximately 750 mV, and the applied potential used was +0.5 V vs. Ag/AgCl. The mean recovery of GSH added during the sample pretreatment step was 95%; the assay imprecision was 1-2% for triplicate analyses of the whole blood samples.