Abstract
The amperometric determination of glucose concentration is classified into two types, oxygen and hydrogen peroxide detector types. The differences in output response of these two detectors are ascribed to the difference of the electrode reaction. Oxygen is reduced to water on the oxygen electrode, while hydrogen peroxide is oxidized to proton and oxygen on the hydrogen peroxide electrode. Since those reaction products, proton and oxygen, relate with the GOD reaction, the sensor current of the hydrogen peroxide detector is considered to be affected by the electrode reaction itself. Theoretical analysis for a rotating-disk electrode covered with an immobilized-enzyme membrane could simulate well experimental outputs of oxygen and hydrogen peroxide electrodes. The output current of the oxygen detector showed asymptotical saturation as glucose concentration increased for the Thiele modulus, MG, rather than unity. The detection limit of glucose concentration, CG,lim increased with increasing concentration of the dissolved oxygen, CO. Oxidation products of hydrogen peroxide affected dominantly with output currents of more than 300 mA·m–2. The CG,lim value of the hydrogen peroxide detector was found to be larger than that of the oxygen detector except for the high CO range at MG = 1.
