A RESPONSE MODEL FOR SURFACE-ACOUSTIC-WAVE ENZYME SENSOR APPLIED TO THE KINETIC-STUDY OF UREASE-CATALYTIC REACTION AND UREA DETERMINATION

A binary substrate-enzyme complex response model based on a surface ac oustic wave (SAW) enzyme sensor has been derived to study enzymatic-ca talytic reactions. It is applied to anon-linear least squares method b ased on Marquardt algorithm by fitting urease-catalytic reaction data. The effect of initial values of rate constants on the programme conve rgence of the proposed method is discussed. The kinetic parameters hav e been estimated and these are of the same order of magnitude as those reported in the literature. As a comparison, the substrate (urea) con centration has been analyzed by the proposed method, the calibration m ethod and the iterative Kalman filter method. The recovery in the case of the proposed method ranges from 98.0% to 103.2% while that for oth er two methods is in the range of 96.0-104.4% and 97.2-103.8% respecti vely. These methods are also used to determine the urea content in hum an blood. The proposed method compares favourably with other methods a nd gives mole precise results.