Lactate (CH₃CH(OH)COO-) plays important roles in many biological processes. Abnormally high concentrations of lactate have been related to disease states such as diabetes and lactic acidosis, etc. L(+)-Lactate is the major lactate stereoisomer formed in human intermediary metabolism and is present in blood. D(-)-Lactate is also present but only at about 1-5% of the concentration of L(+)-Lactate. In the Lactate Assay Kit, lactate is oxidized by lactate dehydrogenase to generate a product which interacts with a probe to produce a color (λmax = 450 nm). The kit detect L(+)-Lactate in biological samples such as in serum or plasma, cells, culture and fermentation media. There is no need for pretreatment or purification of samples. It detects 0.02 mM – 10 mM lactate in various samples.