Enzymatic determination of glutathione using electrochemical sensor based on cobalt phthalocyanine screen-printed electrode

Glutathione (GSH) has been detected with an electrochemical sensor Different types of modified electrode material (screen-printed graphite, graphite-epoxy resin) have been compared. The best results for analytical determination were obtained with screen-printed graphite electrode modified with cobalt phthalocyanine (CoPC) at a potential of 0.20 V vs. saturated calomel electrode (SCE). The analytical determination of GSH is based on the oxidation by a t-butylhydroperoxide catalysed by the enzyme glutathione peroxidase (GSH-Px) in solution, according to: 2GSH + ROOH --> GSSG + H2O + ROH Calibration curves of GSH standard solutions linear up to 30 mu M were obtained in a solution of phosphate buffer (0.05 M phosphate ions, pH = 7) and 0.005 M EDTA. This new procedure seems to be highly reproducible and has the distinct advantage of fast response time, linearity up to 30 mu M of glutathione and a detection limit of 4 mu M.