DETERMINATION OF TRACE-LEVEL OF MERCURY(II) BASED ON THE INHIBITION OF UREASE USING SAW IMPEDANCE ENZYME TRANSDUCER/

A novel and sensitive method for the enzymatic determination of trace amount of mercury ion based on its inhibitory action on urease is prop osed. Mercury(II) inhibits the urease-catalysed urea hydrolysis by bin ding with sulphydryl groups of urease. The inhibited enzymatic reactio n is monitored in-situ with a SAW/impedance enzyme transducer which is composed of a SAW resonator oscillating at 61 MHz and a pair of paral lel electrodes. The inhibition mechanism of Hg(II) on urease is discus sed. The kinetic parameters and inhibition parameters are estimated. T he frequency response of the transducer is proportional to mercury con centration over the range of 50 - 350 ng/mL. The detection limit is 20 ng/mL. The relative standard deviation was 2.9% for sir measurements of 150 ng/mL Hg(II). The effect of potential major interferences was i nvestigated, The method was successfully applied to the determination of Hg(II) in waste water and the results obtained by proposed methods compared well with those obtained by atomic-absorption method.