APPLICATION OF UREASE CONDUCTOMETRIC BIOSENSOR FOR HEAVY-METAL ION DETERMINATION

Urease conductometric biosensors consisting of interdigitated gold ele ctrodes and enzyme membranes formed on their sensitive parts have been used for a quantitative estimation of general water pollution with he avy-metal ions. The measurements of the urease residual activity have been carried out in Tris-HNO3 buffer after preincubation in model meta l-salt solution. The detection limits, depending on preincubation time and dynamic ranges, have been determined in model solutions of heavy- metal ions. The sequence of metals ions relative to their toxicity tow ard urease is: Hg2+ > Cu-2+ > Cd?(2+ > Co2+ > Pb2+ > Sr2+ The conditio ns for practical applications of the, biosensors have been investigate d and critically evaluated for optimization. Urease reactivation by ED TA after inhibition by heavy-metal ions has been demonstrated. The per formance characteristics of the conductometric biosensor are discussed .