Biosensing with coated-wire electrodes. Part 1. Glucose sensors

Abstract

Enzyme electrodes based on fluoride- and iodide-selective coated-wire electrodes are described for the determination of glucose. The electrodes consist of a homogeneous poly(vinyl chloride) membrane containing both the electroactive species and immobilised glucose oxidase. Two enzyme electrodes based on iodide were investigated. The first of these utilised an ammonium molybdate catalyst, yielded a sub-Nernstian calibration with a mean slope of 32 ± 1 mV decade^–1 and had a lifetime of 4 d. The lifetime of the second electrode, for which peroxidase was also immobilised in the electrode membrane, was 6 d. A super-Nernstian calibration was obtained for this electrode with a mean slope of 79 ± 1 mV decade^–1. Finally, the enzyme electrode based on fluoride gave a calibration with a mean slope of 32 ± 1.5 mV decade^–1; this also had a lifetime of 6 d.