An amperometric biosensor for fish freshness detection from xanthine oxidase immobilized in polypyrrole-polyvinylsulphonate film

In this study, new amperometric biosensor for determination of xanthine was developed. Xanthine oxidase with pyrrole and polyvinylsulphonate has been immobilized by entrapment method on the surface of platinum electrode. Determination of xanthine-hypoxanthine was performed by means of oxidation of uric acid liberated during the enzyme reaction on the surface of the enzyme electrode at +0.30V (SCE). The effects of pH, substrate concentration and temperature on the response of the xanthine-hypoxanthine biosensor were investigated. The linear working range of enzyme electrode was 1.0x10-7 ? 1.0x10-3 M of hypoxanthine concentration, the detection limit was 1.0x10-7M. The apparent KM and Vmax of immobilized xanthine oxidase were found to be 0.0154 mM and 1.203 µA / min, respectively. The response current of the biosensor drops to 49% of its initial value after 30 days. The sensor was applied to the determination of hypoxhantine in fish meat and hypoxanthine amount was found to be increased over days of storage.