Reagentless ethanol sensor based on a NAD-dependent dehydrogenase

A reagentless ethanol sensor has been designed based on the coimmobilization of alcohol dehydrogenase (ADH), NADH oxidase and high molecular weight NAD (NAD-dextran) ina poly(vinyl alcohol) bearing stryrylpyridinium groups (PVA-SbQ) matrix. The amperometric detection is based on hydrogen peroxide oxidation by applying a potential difference of 550 mV between two platinum electrodes, equivalent to ca. 600 mV versus SCE. The sensitivity is close to 2 mA.l.mol(-1) (similar to 64 mA.l.mol(-1).cm(-2)), the linear range extends from 3 x 10(-7)M to 10(-4)M ethanol and the response time is lower than 2 min. More than 80 reproducible measurements can be performed without requiring cofactor addition, pointing out a good operational stability. The detection of ethanol concentrations in alcoholic beverages involves dilution of the samples, thus preventing interferences due to oxidizable substances. (C) 1997 Published by Elsevier Science Limited.