Skip to main content

Fast Blue Salt B

Fast Blue Salt B


Chemical structure of Fast Blue Salt B

Common Name: Fast blue salt B
Suggested Name: Fast blue salt B
Other Names:

C.I. Number: 37235
C.I. Name: Azoic diazo 48
Color: Yellow
Solubility Aqueous: 10%
Solubility Ethanol: 10%
Absorption Maximum: 371
Empirical Formula:
Formula Weight: 475.49


Fast blue salt B is a diazonium salt which has been recommended as a coupling agent in a technique which demonstrates aldehydes. 2-hydroxy-3-naphthoic hydrazine is applied to sections in which aldehydes have been generated by some means. The resulting complex then reacts with fast blue salt B forming a blue violet azo dye.

Do not confuse with the textile dye fast blue B (CI 63010, acid blue 45).


  1. R. D. Lillie.
    Conn’s Biological Stains
    Williams & Wilkins, Baltimore, MD., U.S.A.
  2. Culling C.F.A.,
    Handbook of histopathological and histochemical techniques Ed. 3
    Butterworth, London, UK.
  3. Burstone, M.S.
    Enzyme Histochemistry and its application to the study of neoplasms
    Academic Press, New York, NY, USA