The Chronoamperometric and Voltammetric Behaviour of Glutathione at Screen-Printed Carbon Micro-Band Electrodes Modified with Cobalt Phthalocyanine

Screen-printed carbon electrodes (SPCEs) incorporating the electrocatalyst cobalt phthalocyanine (CoPC) have been successfully used for the manufacture of microband electrodes for the determination of reduced glutathione (GSH). Initially investigations were performed to explore the cyclic voltammetric behaviour of these electrodes with potassium ferrocyanide. It was shown that steady state behaviour occurred which is indicative of radial diffusion at a microelectrode. Current densities of 2173 μAcm 2 were obtained compared to 464.4 μAcm 2 for conventional sized (3 mm x 3 mm) screen-printed electrodes were obtained. At scan rates between 5 and 20 mVs 1 no significant increase in current response was observed. The application of these microband CoPC–SPCEs, to the measurement of GSH by both chronoamperometry and cyclic voltammetry was investigated. The chronoamperometric response was found to be linear between 50 μM and 8.0 mM with a detection limit of 7.3 μM using an applied potential of +0.25 V (vs. Ag/AgCl).