AN ENZYMATIC CLAY-MODIFIED ELECTRODE FOR AEROBIC GLUCOSE MONITORING WITH DOPAMINE AS MEDIATOR

Considering the unique adsorption and regeneration properties of dopam ine, glucose oxidase, and nontronite, a glucose sensor was constructed by immobilizing glucose oxidase and nontronite clay coating on a glas sy carbon electode with dopamine as mediator. The response of the gluc ose sensor was determined by measuring the cyclic voltammetric oxidati on peak current values of dopamine under aerobic solution conditions. The effects of the amount of enzyme immobilized, the operating pH, and the common interferences on the response of the glucose sensor were s tudied. The detection limit was 7.4 mu M (S/N = 3), with a linear rang e extending to about 10 mM, giving a dynamic range of about 3 orders o f magnitude for 0.8 mM dopamine. When stored in pH 7 phosphate buffer at 4 degrees C, the sensor shows almost no change in performance after operating for 45 days.