QUINONE-MEDIATED GLUCOSE-OXIDASE ELECTRODE WITH THE ENZYME IMMOBILIZED IN POLYPYRROLE

A composite polypyrrole/glucose oxidase electrode prepared by electropolymerization of pyrrole and the enzyme in a mixture of phosphate buffer (pH 7) and LiClO4 was used for the measurement of the response of glucose. p-Benzoquinone as a mediator showed good reactivity for reoxidation of the reduced form of glucose oxidase and provided a high detection current. Anodic oxidation of the reduced form of the mediator (hydroquinone) took place at the polypyrrole electrode in the potential range where polypyrrole remained in its conductive state. The results indicated a high sensitivity of the electrode, which showed a linear response for concentrations of glucose up to 0.01 M. The response depended on the mediator concentration and on the polymerization conditions of polypyrrole. At the stationary electrode, the anodic current of hydroquinone reached a steady value, which was higher than the current on a rotating electrode, which was independent of the rotation rate in the range from 100 to 2500 rpm. This behaviour could be attributed to a limitation of the rate by the chemical reaction producing hydroquinone.