Enzyme Electrodes For L-Glutamate Using Chemical Redox Mediators and Enzymatic Substrate Amplification

L-glutamate was determined by recycling in a bienzyme system consisting of glutamated dehydrogenase and glutamate pyruvate transaminase. The NADH produced in the dehydrogenase reaction was determined either by direct oxidation at a modified graphite electrode or by reoxidation with oxygen through a N-methylphenazinium ion mediator. The oxygen was determined with an oxygen electrode. The former system resulted in an amplification of 15 and the latter of 60 times.The detection limits became 5-10−7 and 1-10−7 M L-glutamate for the respective systems.