TMB

TMB or 3,3',5,5'-Tetramethylbenzidine is a chromogenic substrate used in staining procedures in immunohistochemistry as well as being a visualising reagent used in enzyme-linked immunosorbent assays (ELISA). In these procedures, TMB turns blue upon oxidation, often by the action of peroxidase. The blue coloration is often changed to yellow by the addition of sulfuric or phosphoric acid. This reaction is often used in research laboratories, clinical laboratories, and in some medical tests.

Chemistry

TMB is a white crystalline powder. It is soluble in organic solvents such as dimethyl sulfoxide (DMSO) and dimethylformamide (DMF). It is slightly soluble in water. The chemical formula of TMB is C16H20N2. It has a molecular weight of 240.35 g/mol.

Applications

TMB is used in a variety of applications in the medical and scientific fields. It is most commonly used as a chromogenic substrate for the detection of horseradish peroxidase (HRP) in ELISA. In this application, TMB is oxidized by HRP in the presence of hydrogen peroxide (H2O2) to produce a blue color. The reaction can be stopped by the addition of a sulfuric or phosphoric acid, which changes the color to yellow. The intensity of the yellow color is directly proportional to the amount of HRP present in the sample.

TMB is also used in immunohistochemistry to detect the presence of specific antigens in tissues. In this application, TMB is used as a substrate for peroxidase, which is linked to an antibody that binds to the antigen of interest. The resulting blue color indicates the location of the antigen in the tissue.

Safety

TMB is a hazardous substance. It is harmful if swallowed, inhaled, or absorbed through the skin. It can cause eye, skin, and respiratory irritation. It is also a potential mutagen. Therefore, it should be handled with care, using appropriate personal protective equipment.

See also

• ELISA
• Immunohistochemistry
• Peroxidase
• Antigen

TMB Resources
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