The Amplex Red H2O2 Assay kit utilizes the Amplex Red reagent and horseradish peroxidase (HRP) to detect H2O2 in biological samples, such as cells and enzyme reactions. Because cells secrete H2O2 into their surrounding environment, cells under oxidative stress can be evaluated by measuring their extracellular H2O2 levels using the Amplex Red assay. When combined with HRP, Amplex Red reagent reacts with H2O2 to produce resorufin, a fluorescent red oxidation product. Resorufin has an excitation range of 530-560 nM and can be detected at a fluorescence emission wavelength of 590 nM. Alternatively, the signal can also be read spectrophotometrically at an absorbance of 560 nM.