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Nitro Blue Tetrazolium

Nitro Blue Tetrazolium

Ionisation: Basic

Common Name: NBT
Suggested Name: Nitro blue tetrazolium
Other Names:

Nitro BT

C.I. Number:
C.I. Name:
Color: Blue
Solubility Aqueous: Soluble
Solubility Ethanol: Soluble
Absorption Maximum:
Empirical Formula: C40H30N10O6Cl2
Formula Weight: 817.7


Nitro blue tetrazolium chloride is probably the most commonly used of the tetrazolium salts in dehydrogenase enzyme histochemistry due to the fine precipitate of the formazan. As the enzyme removes hydrogen from the substrate it is transferred to a hydrogen acceptor, usually a co-enzyme. From the co-enzyme it is transferred to the tetrazole, which is consequently reduced to its insoluble and intensely coloured formazan. The formazan of NBT is deep blue and clearly visible.


  1. R. D. Lillie.
    Conn’s Biological Stains
    Williams & Wilkins, Baltimore, MD., U.S.A.
  2. Aldrich chemical catalogue, 1992
    Aldrich Chemical Company, Milwaukee, WI, USA.
  3. Burstone, M.S.
    Enzyme Histochemistry and its application to the study of neoplasms
    Academic Press, New York, NY, USA