Enzymatic determination of serum urea on the surface of silicone rubber pads

Abstract

An enzymatic, fluorometric method is described for determination of serum urea on silicone rubber pads. In this method, the reagents are lyophilized on the surface of the pads, nicotinamide adenine dinucleotide (hydrolized) (NADH) on one side and a mixture of urease, glutamate dehydrogenase, and α ketoglutarate on the other. The rate of disappearance of NADH fluorescence at 460 nm (excitation wavelength, 340 nm) is monitored and related to serum urea concentration. The calibration curve is linear to 250 mg of urea per liter. The method affords a rapid, simple and inexpensive means for urea assay, the results of which correlate well with automatic diacetyl monoxime method (correlation coefficient, 0.998).