SENSITIVE SPECIALIZATION ANALYSIS OF UREA IN HUMAN BLOOD BY SURFACE-ACOUSTIC-WAVE UREA SENSOR SYSTEM

A novel and sensitive enzymatic method for the determination of micro amounts of urea in human blood has been developed based on the surface acoustic wave (SAW) urea sensor system, which was prepared by combini ng a SAW device with urease (E.C. 3.5.1.5) extracted directly from wat ermelon seeds. The Michaelis constant and maximum rate of the urease w ere estimated as 1.77 mM and 6.82 kHz/min respectively at pH 7.2 and 2 5.0 degrees C. Influences of pH, temperature, and potential major inte rferences on the frequency response of the SAW urea sensor system were investigated. Analysis of urea in control blood plasma samples gave r ecovery between 95% and 105%. The proposed method allows the determina tion of 0.5-15 mu g/mL urea and has a detection limit of 0.50 mu g/mL (8.3 x 10(-6) M. The proposed sensor system has been successfully appl ied in the sensitive specialization analysis of urea in human blood sa mples. The results are consistent with the reported values and also su pport clinical diagnoses. (C) 1996 Academic Press, Inc.