Electrochemical Glucose Oxidation on a Platinized Platinum Electrode in Krebs‐Ringer Solution: II . Potentiostatic Studies

Abstract

The kinetics of the anodic oxidation of glucose in a calcium‐free, Krebs‐Ringer bicarbonate buffer solution at 37°C was studied with a platinized platinum rotating‐disk electrode. Potentiostatic measurements were performed over a potential range of −200 to about 200 mV vs. the saturated calomel electrode (SCE). Excellent reproducibility was achieved by activating the electrode prior to each measurement by an electrochemical pulsing procedure, The current‐time curves did not attain a steady‐state value even after several hours, suggesting that a slow deactivation of the electrode was occurring during the glucose oxidation reaction. Over a limited potential range the current decay exhibited a logarithmic dependence on time. This behavior was interpreted in terms of adsorption of an inhibiting species according to the Elovich equation. The variation of glucose oxidation rate as a function of electrode rotation rate showed that the reaction was predominantly activation controlled. Calculated values of , the over‐all charge transfer number for glucose oxidation, were dependent upon both potential and time and ranged from about 4 to 20 under the conditions studied.