Electrodeless Piezoelectric Quartz Crystal Sensor for Determination of Total Urinary Reducing Sugar

Abstract A glucose-sensing system was developed in which an electrodeless piezoelectric quartz crystal was used to measure mass changes on the surface of a quartz plate during the reduction of Ag(NH 3 ) + 2 by glucose. A satisfactory correlation was obtained between the frequency shift and the glucose concentration in the range 1.0–25 mM, and the total reducing sugar in urine was determined. Treatment with 8 M nitric acid after each measurement was effective for cleaning the quartz surface, and the electrodeless piezoelectric quartz crystal sensor possessed excellent reproducibility and reusability during repeated use over 400 times. For the determination of total reducing sugar in urine (or blood), the present method can avoid the interferences occurring in a colorimetric method such as the color and turbidity of clinical specimens.