EFFECT OF INTERFERENCE ON THE PERFORMANCE OF GLUCOSE ENZYME ELECTRODES USING NAFION(R) COATINGS

The negatively charged perfluorinated ionomer Nafion(R) was used as a coating on hydrogen peroxide detecting platinum electrode as well as o n a polycarbonate diffusion membrane in the construction of a glucose amperometric enzyme electrode. The current response of these electrode s to hydrogen peroxide, ascorbic acid, acetaminophen, uric acid and gl ucose was studied and the coating procedure was optimized. It was conf irmed that the Nafion(R) coating prevents interference by anionic subs tances such as ascorbic acid and uric acid, and decreases acetaminophe n interference. In this regard it was shown that coating the glucose d iffusion membrane (polycarbonate) was more effective than coating the platinum wire itself; because of the prevention of the homogeneous red ox reaction of the interference species with hydrogen peroxide, as wel l as the additional diffusional resistance to the glucose flux. The gl ucose levels in serum samples were estimated and the stability of the enzyme electrodes during continuous operation in serum was studied An enzyme electrode with constant sensitivity of ca. 1 mu A/mM and a line ar range of up to 15 mM, unaffected by contact with serum, is reported .