An assay for the determination of the amount of glucose oxidase immobilised in an enzyme electrode

This paper presents a simple assay for the estimation of the amount of glucose oxidase immobilised onto the surface of enzyme electrodes. The two flavin adenine dinucleotide (FAD) cofactors were stripped from immobilised glucose oxidase using an 8 M urea solution. The resultant concentration of FAD in the urea solution was quantified using either fluorescence or voltammetry to determine the amount of glucose oxidase on the electrode surface. The assay is applied to a variety of different enzyme electrodes and is verified for a monolayer enzyme electrode using a quartz crystal microbalance.