INVESTIGATIONS OF PLATINIZED AND RHODINIZED CARBON ELECTRODES FOR USE IN GLUCOSE SENSORS

Graphite electrodes were modified by the electrodeposition of either platinum or rhodium, using cyclic voltammetry. Following only brief periods nf treatment, plantinized carbon electrodes were able to directly oxidize glucose at a potential of +350 mV (vs. Ag/AgCl). By narrowing both the potential range of deposition (-450 to -500 mV) and cycling period (50 seconds at a scan rate of 10 mV s(-1)), the effects of direct glucose oxidation could be significantly: reduced. Detection of H2O2 at +400 mV was possible; glucose enzyme electrodes were constructed, with glucose oxidase immobilized in hydroxyethylcellulose and operated at this potential. These sensors had a linear range of 0.1 to 25 mM glucose and a slope of 8 nA/mM. Other electrodes were prepared by the electrodeposition of rhodium. These base electrodes proved to be insensitive to glucose and produced higher currents (compared to low platinum electrodes) to H2O2. Glucose sensors were constructed using rhodinized electrodes. Again operating at +400 mV, these sensors had a linear range from 0.1 to 20 mM and a slope of 21 nA/mM glucose.