Amperometric Determination of Urea Using Enzyme-Modified Carbon Paste Electrode

摘要

An amperometric biosensor based on carbon paste electrodes (CPEs) for the determination of urea was constructed by enzyme (urease/GL-DH)-modified method. Urea was hydrolyzed to NH4+ by catalyzing urease onto the enzyme-modified electrode surface in sample solution. In the presence of メ-ketoglutarate and reduced nicotinamide adenine dinucleotide(NADH), a liberated NH4 + produce to L-glutamate and NAD+ by Lglutamate dehydrogenase (GL-DH). After the chemical reaction was proceeded, the electrochemical reaction was occurred that an excess of the NADH was oxidized to NAD+. The oxidation current of NADH was monitored at +1.10 volt vs. Ag/AgCl. An optimum conditions of biosensor were investigated: The optimum pH range for catalyzed hydrolysis reaction of urea was pH 7.0-7.4. The linear response range and detection limit were 2.0 】 10?5~2.0 】 10?4 M and 5.0 】 10?6 M, respectively. Another physiological species did not interfere, except L-ascorbic acid.