Analytical Performance of a Glucose Biosensor Prepared by Immobilization of Glucose Oxidase and Different Metals into a Carbon Paste Electrode

Enzymatic metallized carbon paste electrodes prepared by incorporation of mixtures of different metals into the paste offer a substantial decrease in the overvoltage for hydrogen peroxide oxidation and reduction. Dramatic improvements in the sensitivity and selectivity for glucose determination were obtained after the addition of iridium into carbon paste electrodes (CPE) containing glucose oxidase and palladium, copper or ruthenium. In all cases a synergistic effect was observed with a large enhancement in sensitivity obtained specially in the case of palladium-composite materials. The improvement in selectivity was more evident in the case of copper and palladium carbon paste enzymatic electrodes containing iridium where even in the presence of large excess of ascorbic acid, uric acid and acetaminophen, no interference was observed. A linear relationship between current and glucose concentration was obtained up to 1.5×10−2 M (2.7 g/L) glucose in the case of Pd(2.65%)-Ir(8.00%)-GOx(7.00%)-CPE. The effect of metals and enzyme content on the analytical performance of the bioelectrodes is analyzed.