TOOLS Soluble TMB Substrate
3,3',5,5'-Tetramethybenzidine (TMB) is a substrate for peroxidase-based enzyme immunoassays. Oxidized TMB turns a blue color reaction (measured by 652 nm) results for producing oxygen radicals by the hydrolysis of hydrogen peroxide by HRP. TMB has different absorbance 370 nm or 652 nm. The color changes to yellow with the addition of sulfuric or phosphoric acid with maximal absorbance at 450 nm.