3,3’,5,5’-Tetramethylbenzidine
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Preferred IUPAC name
3,3',5,5'-Tetramethyl[1,1'-biphenyl]-4,4'-diamine
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| Other names
3,3',5,5'-Tetramethylbiphenyl-4,4'-diamine
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.053.949 |
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| Properties | |
| C16H20N2 | |
| Molar mass | 240.3482 g/mol |
| Melting point | 168 to 171 °C (334 to 340 °F; 441 to 444 K) |
| Hazards | |
| Safety data sheet | External MSDS |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is   ?) |
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| Infobox references | |
3,3’,5,5’-Tetramethylbenzidine or TMB is a chromogenic substrate used in staining procedures in as well as being a visualising reagent used in enzyme-linked immunosorbent assays (ELISA). TMB is a white crystal powder that forms a pale blue-green liquid in solution with ethyl acetate. TMB is degraded by sunlight and by fluorescent lights.
TMB can act as a hydrogen donor for the reduction of hydrogen peroxide to water by peroxidase enzymes such as horseradish peroxidase.
The resulting diimine causes the solution to take on a blue colour, and this colour change can be read on a spectrophotometer at a wavelength of 650 nm.
The reaction can be halted by addition of acid or another stop reagent. Using sulfuric acid turns TMB yellow. The colour may be read at 450 nm.
TMB should be kept out of direct sunlight as it is photosensitive. It is not known if TMB is carcinogenic and the evidence is contradictory: TMB is not mutagenic by the Ames test, and did not induce formation of tumors in a single-arm study of 24 rats. On that evidence, it has been used as a replacement for carcinogenic compounds such as benzidine and o-phenylenediamine.
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