Quantitation of glucose concentration using a glucoseoxidase-catalase electrode by potentiometric measurement

Glucose oxidase and catalase were immobilized in polyacrylamidegel around a platinum screen and used to measure the concentration of glucose in 0.1 M phosphate buffer, pH 7.3, at 37°C. This enzyme electrode produced a direct potentiometric signal with reference to a standard Ag{norm of matrix}AgCl electrode. The potential difference was linearly related to the logarithm of the concentration of glucose over the range of 3-40 cg/dm³ (mg/dl). The electrode was stable for at least 32 hours at 37°C. Hydrogen peroxide, generated by the oxidation of glucose and depleted by decomposition and diffusion, was the apparent source of the potentiometric signal. Direct potentiometric measurement has the advantages of simple readout, continuous detection, and small electrode size, and does not require external polarising potential. This approach should be suitable for the continuous in vivo monitoring of blood glucose levels if the upper limit of specificity for glucose (presently 40 mg/dl) can be extended.