Enzymatic Determination of Glutathione Using Electrochemical Sensor Based on Cobalt Phthalocyanine Screen-printed Electrode

M. A. Carsol, I. Pouliquen-Sonaglia, G. Lesgards and M. Mascini*

Faculté des Sciences et Techniques d'Aix-Marseille III, Avenue Escadrille, Normandie Niemen, 13397 Marseille, France

*Università degli Studi di Firenze, Dipartimento di Sanità Pubblica, Epidemiologica e Chimica Analitica Ambientale, Sez: Chimica Analitica Via G. Capponi, 9, 50121 Firenze, Italy

Article history:

Received March 12, 1996 
Accepted August 14, 1996

Key words:

glutathione, electrochemical sensor, screen-printed graphite electrode, cobalt phthaIocyanine, glutathione peroxiclase

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 + ROOM → GSSG + H2O + ROH. Calibration curves of GSH standard solutions linear up to 30 µM 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 µM of glutathione and a detection limit of 4 µM.