Dh. Liu et al., DETERMINATION OF TRACE-LEVEL OF MERCURY(II) BASED ON THE INHIBITION OF UREASE USING SAW IMPEDANCE ENZYME TRANSDUCER/, Analytical letters, 28(8), 1995, pp. 1323-1337
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.