CHRONOCOULOMETRIC INTERROGATIONS OF OXIDASE-BASED ENZYME ELECTRODES FOR ENHANCED SELECTIVITY

Classical oxidase-based enzyme electrodes rely on the amperometric det ermination of H2O2. Such electrodes are vulnerable to electroactive in terferants found in biological solutions. Some interferants may be oxi dized at anodic potentials, necessitating the use of permselective bar rier membranes. Two generic chronocoulometric approaches to the interr ogation of oxidase-based enzyme electrodes have been developed. Both t he chronocoulometric interrogation of H2O2, and the chronocoulometric interrogation of the reduction of O-2 (formed from the anodic oxidatio n of H2O2) have allowed new correlations to be made with O to 20 mM gl ucose concentrations. Furthermore, the interrogation of O-2 has allowe d a glucose sensor to be constructed that is virtually free from the e ffects of electroactive interferants.