An Amperometric Glucose Electrode Based on Adsorbed Glucose Oxidase on Palladium/Gold Modified Graphite

Abstract

A glucose electrode was constructed by adsorbing glucose oxidase (GOD) on a modified electrode for H₂ O ₂ oxidation, consisting of Pd/Au sputtered on graphite. Maximally, 0.8 U cm⁻² of GOD could be adsorbed. The electrode was used in a f.i.a. manifold for determination of glucose. Linear calibration curves were obtained in the concentration range 3. 10⁻⁶ 4. 10⁻³ mol L⁻¹ glucose. The applied potentials for glucose determination were + 300 mV vs. Ag/AgCl at pH 8.0, + 350 mV at pH 7.0, + 400 mV at pH 6.0 and + 500 mV at pH 5.0. The activity vs. pH profile of adsorbed GOD was broad having an optimum between pH 5 and 6. The apparent kinetic parameters for adsorbed GOD, K_M ^app and i_max, were found to be 50 mM and 160 uA at optimal pH.