Simultaneous Electrochemical Determination of Glutathione and Glutathione Disulfide at a Nanoscale Copper Hydroxide Composite Carbon Ionic Liquid Electrode

Abstract

Direct simultaneous electrochemical determination of glutathione (GSH) and glutathione disulfide (GSSG) has been presented using a nanoscale copper hydroxide carbon ionic liquid composite electrode. To the best of our knowledge, this is the first report on the simultaneous determination of these two biologically important compounds based on their direct electrochemical oxidation. Incorporation of copper(II) hydroxide nanostructures in the composite electrode results in complexation of Cu(II) with the thiol group of GSH and leads to a significant decrease in GSH oxidation overpotential, while an anodic peak corresponding to the direct oxidation of GSSG as the product of GSH oxidation is observed at higher overvoltages. Low detection limits of 30 nM for GSH and 15 nM for GSSG were achieved based on a signal-to-noise ratio of 3. The proposed method is free from interference of cysteine, homocysteine, ascorbic acid (AA), and uric acid (UA). No electrode surface fouling was observed during successive scans. Stability, high sensitivity, and low detection limits made the proposed electrode applicable for the analysis of biological fluids.