SILK FIBROIN CELLULOSE ACETATE MEMBRANE ELECTRODES INCORPORATING XANTHINE-OXIDASE FOR THE DETERMINATION OF FISH FRESHNESS/

A bilayer coated-wire electrode incorporating xanthine oxidase is repo rted to estimate fish freshness. The modified electrode is constructed with two membranes, a silk fibroin membrane with immobilized enzyme a nd a cellulose acetate membrane to eliminate the interference from hig h molecular weight compounds such as proteins. The biosensor is based on detecting hydrogen peroxide released from the enzymatic reaction. i t shows high sensitivity and long-time stability for fish samples. The minimum concentration of hypoxanthine that could be detected was 1 x 10(-7) mol l(-1). Due to the protection of the cellulose acetate membr ane, the electrode was stable for six weeks or 400 assays of fish tiss ue samples. The results were in good agreement with those of tradition al assays for determination of the freshness of some kinds of river fi shes. (C) 1998 Elsevier Science B.V. All rights reserved.