A coupled enzymatic method to measure blood lactate by amperometric monitoring of the rate of oxygen depletion with a Clark oxygen electrode.

A rapid, sensitive and reliable method to measure lactate in blood is described. The method is based on the enzymatic oxidation of lactate to pyruvate in the presence of nicotinamide adenine dinucleotide (NAD+) and lactate dehydrogenase (LDH). The reaction product, NADH, is then oxidized by molecular oxygen, carried in the buffered reagent medium, in the presence of horeseradish peroxidase and other cofactors. The maximum rate of oxygen depletion, which is directly proportional to the amount of lactate ion present in the sample, is amperometrically monitored by a membrane oxygen electrode. No sample pretreatment is required in the present procedure other than dilution, and a comparison study between the described method and a spectrophotometric method shows good correlation.