Nonenzymatic glucose detection with good selectivity against ascorbic acid on a highly porous gold electrode subjected to amalgamation treatment

A nonenzymatic glucose sensor with good selectivity for the ascorbic acid oxidation is presented. After the gold polycrystalline electrode was subjected to amalgamation treatment, two advantageous effects were observed. One is the enhancement of the surface roughness and the other is an increase in the catalytic current in the glucose oxidation. Besides the known first effect, the latter provided another advantageous effect in a fabrication of nonenzymatic glucose sensor. Using a gold electrode subjected to amalgamation treatment for 60 s, two calibration curves for glucose oxidation at two different potentials of -0.1 V and 0.25 V were obtained and compared. At the potential of -0.1 V, at which no ascorbic acid was oxidized and no interference effect was observed, a current sensitivity of 16 mu A cm(-2) mM(-1) from zero to 10 mM glucose concentration range was obtained. At the other potential of 0.25 V, at which ascorbic acid was easily oxidized, a satisfactory calibration curve with negligible ascorbic acid interference was also obtained together with a more enhanced current sensitivity of 32 mu A cm(-2) mM(-1).