Flow Injection Analysis of Lactate and Lactate Dehydrogenase Using an Enzyme Membrane in Conjunction with a Modified Electrode

Abstract
A modified electrode for H2O2 oxidation, consisting of Pd/Au sputtered on carbon was covered with a lactate oxidase membrane and used in a FIA manifold for selective determination of lactate. The linear range was 0.01-3 mM lactate and up to 200 samples per hour were measured with a relative standard deviation of 1%. Interferences from ascorbic acid and NADH were small because of the low potential of the modified electrode. The lactate oxidase membrane electrode was also used for measurement of lactate dehydrogenase activity using direct injection of the sample into a carrier stream containing pyruvate and NAD+.