Optimal Conditions for the Enzymatic Determination of L-Lactic Acid

Abstract A simple enzymatic method for the determination of lactic acid with muscle lactic dehydrogenase is described. L(+) Lactate in amounts from 0.04 µM to 0.4 µM can be directly measured by following the formation of reduced diphosphopyridine nucleotide at 340 mµ. The effect of varying the concentrations of reactants in the test system was studied, and the optimal concentrations for stoichiometric conversion of lactate to pyruvate were determined. When lactic acid concentrations in plasma, liver, and heart muscle were determined by both enzymatic and chemical methods, identical results were obtained. The advantages of the present enzymatic procedure over chemical methods are discussed.