AbstractAn amperometric sol‐gel‐based enzyme inhibition electrode for the detection of low levels of cyanice was constructed by immobilizing horseradish peroxidase (HRP) and an osmium redox polymer ([Os(bpy)2(PVP)10Cl]Cl; abbreviated Os‐polymer) as mediator. Upon addition of hydrogen peroxide to the solution, a bioelectrocatalytic reduction wave was observed, which was diffusion controlled. This reduction current is subsequently inhibited by cyanide. The steady‐state hydrogen peroxide catalytic reduction current reached a plateau at 150 mV (vs. Ag/AgCl) and cyanide could be determined amperometrically with good sensitivity at 0mV (vs. Ag/AgCl). The concentration range of linear response, apparent inhibition constant (K), and detection limit were 0.004–0.04 mM, 0.0637 mM, and 0.5 μM, respectively. Sodium azide, potassium thiocyanide and thiourea were all found not to interfere at this potential. The biosensor was found to be stable for over 1 week on storage at room t
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