Effect of interference on the performance of glucose enzyme electrodes using Nafion coatings.

The negatively charged perfluorinated ionomer Nafion was used as a coating on hydrogen peroxide detecting platinum electrode as well as on a polycarbonate diffusion membrane in the construction of a glucose amperometric enzyme electrode. The current response of these electrodes to hydrogen peroxide, ascorbic acid, acetaminophen, uric acid and glucose was studied and the coating procedure was optimized. It was confirmed that the Nafion coating prevents interference by anionic substances such as ascorbic acid and uric acid, and decreases acetaminophen interference. In this regard it was shown that coating the glucose diffusion membrane (polycarbonate) was more effective than coating the platinum wire itself, because of the prevention of the homogeneous redox reaction of the interference species with hydrogen peroxide, as well as the additional diffusional resistance to the glucose flux. The glucose 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 microA/mM and a linear range of up to 15 mM, unaffected by contact with serum, is reported.