Dip-coated electroenzymic glucose transducer
Springer Online Journal Archives 1860-2000
Chemistry and Pharmacology
Abstract The details of construction and the performance characteristics of a dipcoated electroenzymic glucose transducer comprising an H2O2 electrode coated with a layer of glucose oxidase encapsulated in cellulose acetate and overlaid with a layer of polyurethane are presented. The steady-state current increases when the glucose oxidase and cellulose acetate concentrations of the dip-coating solutions are increased, but high cellulose acetate concentrations yield thick and mechanically unstable membranes. A compromise between current yield and mechanical stability can, however, be achieved by employing glucose oxidase and cellulose acetate concentrations of 200 mg ml−1 and 2–5 g 100 ml−1, respectively. A polyurethane concentration of 6 g 100ml−1 is optimal both in terms of the current yield and the linearity of response. The relationship between steady-state current and D-glucose concentration is approximately linear over the concentration range 0·5 to 11·5 mm, and if correction is made for deviations from linearity at higher glucose concentrations, concentrations in excess of 20 mM can readily be quantified. The steady-state current is pH and temperature dependent, but the dependencies are relatively small in the physiological range. The mean rate of decrease of the glucose current during long-term operation of the optimised transducer is 0·83 per cent of the initial current per hour at 37°C. The hydrated electrodes perform satisfactorily after storage for more than two weeks at room temperature. the transducers have a mean response time [t 90%] of 50 s or less.
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