Enzyme electrode for glucose determination in whole blood

The development of a glucose sensor suitable for use with whole blood is described. It is based on anodic oxidation at +700 mV of hydrogen peroxide with a platinum electrode covered with a gas permeable membrane. Glucose reacts with glucose oxidase immobilised on the external side of the membrane, and forms hydrogen peroxide which is able to cross the gas permeable membrane due to its high vapour tension, while other electroactive substances that are important interferents are completely blocked. This principle was discovered several years ago but no practical application was presented up to now. Therefore in this work a number of different commercial membranes were tested, in order to obtain a resistant, rapidly responding and interference free sensor to be used in conjunction with a blood gas measurement apparatus. Coimmobilisation of glucose oxidase and catalase was found to be useful for fast response and recovery of the electrode. Using some of the tested membranes, the linearity range is 1-15 mM, CV 5%, response time 90 s, recovery time for the next sample 120 s. The membrane's working life is 2-3 weeks.