COMPARISON OF IMMOBILIZATION PROCEDURES FOR DEVELOPMENT OF AN ELECTROCHEMICAL PPO-BASED BIOSENSOR FOR ON LINE MONITORING OF A DEPURATION PROCESS

The development of amperometric biosensors based on polyphenol oxidase (PPO) as a novel tool for the determination of phenolic compounds is described. Biosensors have been obtained using different PPO-rich matrices: tissue slices from mushroom and potato, acetonic powder from mushroom; lyophilised enzyme from mushroom (tyrosinase-SIGMA). A large variety of immobilisation procedures have been used with pure enzyme and acetonic powder. Behaviour of all biosensors obtained has been investigated in terms of sensitivity, linearity range, response time and half life time. Preliminary experiments have been carried out, using a Flow Injection Analysis, with standard solutions of catechol and phenol in the range 1-10 mM, then biosensors have been also tested on a real sample (green water from crushers) with a direct method and a standard addition, one obtaining good reproducibility.