TMB (single-component)

TMB (3,3',5,5'-tetramethylbenzidine) is a widely used chromogenic substrate for the enzyme horseradish peroxidase (HRP), primarily in ELISA (enzyme-linked immunosorbent assay), Western blotting, and immunohistochemistry. It reacts with HRP to produce a distinct blue color, which can be measured directly or stopped with an acid to yield a yellow product for precise intensity measurement. TMB is also used in the TMB test for detecting blood, as it reacts with hemoglobin to produce a blue-green color.