Potentiometric determination of NAD(P)H coenzymes using a nitrite-selective membrane electrode and a nitrate reductase enzyme and the application to glucose assay in human serum

NAD(P)H coenzyme concentrations were determined with the combination of a n itrite-selective membrane electrode and a nitrate reductase enzyme. The met hod was based on the detection of nitrite formed by the enzymatic reaction of NAD(P)H with nitrate catalyzed by nitrate reductase. The lower detection limits for both these coenzymes were around 100 mu M. This system was appl ied to detect glucose by combining an additional glucose dehydrogenase enzy me. Serum glucose levels could be determined through the detection of nitri te.