Amperometric determination of alcohols, aldehydes and carboxylic acids with an immobilized alcohol oxidase enzyme electrode.

Chemical tests for measurement of blood alcohols are the subject of much interest. particularly in legal cases, and there is a need for quick, simple and reliable assay methods. Likewise. the determinations of carboxylic acids and aldehydes are of importance in various industrial fields, but such assays are difficult to carry out. especially at low concentrations. In the past. alcohols_ have been determined by gas chromatograplry1-3. spectrophotometry4*’ and rcdox titration”.‘. Selective spectrophotometric enzymatic methods utilizing alcohol dehydrdgenase have been reported’-“. but it is not possible to couple these with an electroanalytical device such as an ion-selective electrode; these methods also require a coenzyme. NAD. and deproteinization of the serum sample before U.V. measurement. Guilbault and Lubrano” used a new enzyme for assay of alcohol, alcohol oxidase, by amperometrically detecting the hydrogen peroxide formed during the enzymatic reaction. Because the activity’ of the available enzyme was low. it was not possible to immobilize the enzyme and to build an enzyme electrode in a method similar to that described for assay of g1ucose’2*13. Hence, measurements were conducted only in bulk solution with soluble enzyme. In this study, an alcohol enzyme electrode which was useful for the assay of blood ethanol in concentrations as low as 10 mg ‘%, is described. Additionally, this chemically bound alcohol oxidase electrode was found to be useful for the assay of aldehydes and carboxylic acids based on a measurement of the consumption of dissolved oxygen in the enzymatic reaction, similar to that used in the uricase-uric acid systemi4.