Amperometric biosensors have received considerable attention in the last years due to the advantages inherent to the combination of the biocatalytic reactions specificity and the amperometríc transductíon sensitivity. Several strategies have been developed for improving the selectivity of amperometric bioprobes and metallized carbon electrodes have been successfully used in this direction.

This communicatíon describes the analytical performance and kínetic behaviour of two metallized bioelectrodes for glucose quantification: carbon paste containing gold microparticles and glucose oxidase (GOX), and glassy carbon with electrodeposited iridium and GOx.

The determinations were performed amperometrically in 0.050 M phosphate buffer solution + 0.030 M NaClpH 7.4 from the enzymatically generated hydrogen peroxide. The influence of the bioelectrode composition on the sensitivity and kinetic parameters was analyzed. The selectivity towards ascorbic and uric acids was also evaluated.

The electrocatalytic action of gold and iridium allows the cathodic detection of hydrogen peroxide at -0.10V, facilitatíng the development of remarkable selective glucose bioprobes even in the large excess of ascorbic and uric acids.

Enzymatic carbon electrodes doped with different metals exhibit different electrocatalytic activities and hence analytical performance. The notorious decrease in the operating potential greatly benefits the amperometric monitoring of glucose.