L-Malate, the anionic form of L-malic acid, is an intermediate in the citric acid (TCA) cycle. It is a source of CO2 in plants, improves muscle performance post-exercise, and can act as a metal chelator. Cayman's Malate Fluorometric Assay provides a fluorescence-based method for detecting malate from plasma, serum, urine, tissue homogenates, and cell culture samples. This assay utilizes an enzymatic reaction in which L-malate dehydrogenase catalyzes the oxidation of L-malic acid to oxaloacetate, with the concomitant reduction of the fluorescent substrate to yield a highly fluorescent product that can be analyzed with an excitation wavelength of 530-540 nm and an emission wavelength of 585-595 nm.