COMPARISON BETWEEN OUTPUT LINEARITIES OF OXYGEN DETECTOR AND HYDROGEN-PEROXIDE DETECTOR FOR AMPEROMETRIC GLUCOSE SENSORS

The amperometric determination of glucose concentration is classified into two types, oxygen and hydrogen peroxide detector types. The diffe rences in output response of these two detectors are ascribed to the d ifference of the electrode reaction. Oxygen is reduced to water on the oxygen electrode, while hydrogen peroxide is oxidized to proton and o xygen on the hydrogen peroxide electrode. Since those reaction product s, 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 e lectrode covered with an immobilized-enzyme membrane could simulate we ll experimental outputs of oxygen and hydrogen peroxide electrodes. Th e output current of the oxygen detector showed asymptotical saturation as glucose concentration increased for the Thiele modulus, M(G), rath er than unity. The detection limit of glucose concentration, C-G,C-lim increased with increasing concentration of the dissolved oxygen, C-O. Oxidation products of hydrogen peroxide affected dominantly with outp ut currents of more than 300 mA . m(-2). The C-G,C-lim value of the hy drogen peroxide detector was found to be larger than that of the oxyge n detector except for the high C-O range at M(G) = 1.