7-10An amperometric biosensor has been prepared by immobilizing plant tyrosinase enzyme in a novel composite polysaccharide gel matrix on the tip of a glassy carbon electrode and used for the measurements of Dopa substrates in aqueous medium in the concentration range 10-4 to 10-2 mol I-1. The sensor has a shelf-life of four months. Parameters affecting the performance of the sensor have also been evaluated
