Inhibitive determination of mercury and other metal ions by potentiometricurea biosensor

The biosensor with urease entrapped in PVC layer at the surface of pH-sensi tive iridium oxide electrode was applied for testing of mercury and other m etal ions inhibition on enzymatic reaction. The calculation of inhibition e ffect was based on the measurement of initial rate of decrease of biosensor potential (proportional to the initial rate of enzymatic reaction) after a ddition of substrate after inhibition step. Some differences of inhibition extent were observed for various mercury forms (Hg(NO3)(2), HgCl2, PhHgCl a nd Hg-2(NO3)(2)) as well as for other heavy metal ions investigated as pote ntial interferents. Because the method was not specific, it was applied for the determination of total inhibition effect caused by heavy metal ions in water samples. In the case of most cations tested the total recovery of en zyme activity was possible using Tris buffer solution with EDTA and thioace tamide after less than 10 min regeneration time. (C) 2000 Elsevier Science S.A. All rights reserved.