A new strategy for the selective determination of glutathione in the presence of nicotinamide adenine dinucleotide (NADH) using a novel modified carbon nanotube paste electrode

A novel electrochemical sensor for the simultaneous determination of glutathione (GSH) and nicotinamide adenine dinucleotide (NADH) is described. The sensor is based on a carbon paste electrode (CPE) modified with benzamide derivative and multiwall carbon nanotubes. This mixture makes a modified electrode that is sensitive for the electrochemical detection of these compounds. Under optimum conditions and at pH 7.0, oxidation of GSH occurs at a potential of about 330 mV less positive than that at an unmodified CPE. The voltammetric peak currents are linearly dependent on GSH and NADH concentrations in the ranges 0.09–300 μmol L−1 GSH and 5.0–600 μmol L−1 NADH. The detection limits found for GSH and NADH were 0.05 μmol L−1 and 1.0 μmol L−1, respectively. The electrochemical sensor was also used for the determination of GSH in urine, pharmaceutical and hemolysed erythrocyte samples.