3,3',5,5'-Tetramethylbenzidine dihydrochloride (TMB·2HCl) is a widely used chromogenic substrate for peroxidase enzymes, particularly horseradish peroxidase (HRP) in biochemical and immunological assays. Compared with the free base form, the dihydrochloride salt exhibits improved water solubility and handling convenience, making it suitable for aqueous assay systems.
In HRP-catalyzed reactions, TMB is oxidized in the presence of hydrogen peroxide to produce a blue-colored product, which can be further converted to a yellow-colored compound upon addition of acid stop solution. The resulting color change can be quantitatively measured using spectrophotometric methods, enabling sensitive detection in ELISA assays and other enzyme-linked immunoassays.
Due to its strong color development and high sensitivity, TMB dihydrochloride is widely used in immunoassays, diagnostic reagent development, enzyme activity assays, and analytical biochemistry research.
3,3',5,5'-Tetramethylbenzidine dihydrochloride is an aromatic diamine compound that acts as a chromogenic substrate in peroxidase-catalyzed oxidation reactions.In HRP-based detection systems:
The increase in absorbance is proportional to enzyme activity or target analyte concentration in the assay.
TMB dihydrochloride is commonly used as a chromogenic substrate in ELISA assays employing HRP-labeled antibodies.Typical applications include:
The compound is widely used in immunoassay system development, particularly in assays requiring sensitive colorimetric detection.Applications include:
TMB dihydrochloride is also used to evaluate peroxidase enzyme activity in biochemical experiments.Typical uses include:
Because of its sensitivity and reliability, TMB dihydrochloride is widely used in in vitro diagnostic (IVD) reagent development.Applications include:
| Parameter | Recommended Conditions |
| Detection Method | Colorimetric spectrophotometric detection |
| Detection Wavelength | 650 nm (blue product) or 450 nm after acid stop |
| Buffer Systems | Citrate buffer or acetate buffer |
| Temperature | Room temperature (20–25 °C) |
| Assay Format | ELISA microplate assays, enzyme activity assays, immunoassays |
Experimental parameters may require optimization depending on assay conditions.
Researchers working with:
What is 3,3',5,5'-Tetramethylbenzidine dihydrochloride used for?
It is commonly used as a chromogenic substrate for horseradish peroxidase (HRP) in ELISA assays and other enzyme-linked immunoassays.
What wavelength is used to detect TMB reactions?
The oxidized blue product can be measured at 650 nm, while the acid-stopped yellow product is typically measured at 450 nm.
Why use the dihydrochloride form of TMB?
The dihydrochloride form provides better water solubility and easier preparation of assay solutions.
