STUDIES ON ENZYME ELECTRODES WITH FERROCENE AND CARBON PASTE BOUND WITH CELLULOSE TRIACETATE

A ferrocene-based chemically modified electrode has been prepared from a mixture of carbon paste and ferrocene, bound with cellulose triacetate. Glucose oxidase immobilized onto nylon net placed over the chemically modified indicator electrode completed the assembly of a robust ferrocene-mediated enzyme electrode. This was housed in a three-electrode Stelte micro-cell modified for flow injection according to previous studies, and further modified by introducing a viscose acetate exclusion membrane between the outermost nylon-enzyme mesh and the ferrocene-carbon paste layer. Glucose was determined amperometrically by monitoring the product of hydrogen peroxide enzymolysis at + 160 mV versus a silver-silver chloride reference electrode. The enzyme electrodes showed a detection range of 0.01-70 mmol dm-3 glucose and the lifetime of the chemically modified electrode exceeded 24 months with intermittent use. Interference from ascorbic acid was minimal, while the maximum useful range was extended to 100 mmol dm-3 glucose by simply covering the electrode surface with an exclusion membrane. A simplex optimization procedure was employed in evaluating electrodes without the use of an exclusion membrane.