Tetramethylbenzidine

Tetramethylbenzidine (TMB) is an organic chemical compound with the molecular formula C16H20N2. It belongs to the class of aromatic amines and is commonly used as a chromogenic substrate in various analytical assays, most notably in enzyme-linked immunosorbent assays (ELISAs). TMB is characterized by its ability to undergo a colorimetric reaction upon oxidation, changing from colorless or pale yellow to a distinct blue hue, which can be quantified spectrophotometrically.

Chemically, TMB is a symmetrical benzidine derivative, featuring four methyl groups attached to the benzidine backbone, which influence its reactivity and solubility. It is typically supplied as a solution in a suitable solvent, such as dimethylsulfoxide or acetonitrile. Due to its oxidative properties, TMB is often used in conjunction with peroxidase enzymes like horseradish peroxidase (HRP), which catalyze its oxidation in the presence of hydrogen peroxide. This reaction produces a stable, colored product that correlates with the presence and quantity of target analytes.

TMB's usefulness in bioassays is complemented by its relatively low toxicity compared to other chromogenic substrates. However, it requires careful handling and disposal, as it is classified as a hazardous chemical. In laboratory settings, TMB is widely employed for detecting biological molecules such as antibodies, antigens, and other biomolecules, making it an essential tool in diagnostics, research, and quality control processes.

Safety precautions include working in a well-ventilated area, wearing protective gloves, and avoiding inhalation or ingestion. Its high sensitivity, specificity, and ease of use have established TMB as a standard reagent in immunological testing across biomedical laboratories worldwide.