TMB

TMB: 3,3’,5,5’-Tetramethylbenzidine (TMB) is a colorimetric substrate used with peroxidase and peroxidase-coupled systems. It produces a soluble end product, which is blue in color and can be read spectrophotometrically at 370 nm or 655 nm. The reaction can be stopped with 2 M sulfuric acid and read at 450 nm. This results in a 2–4 fold enhancement of the sensitivity of the reaction. This product is also been used in the quantitative determination of hemoglobin and cytochemical staining for peroxidase.