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Eosin B

Eosin B

Class: Fluorone
Ionisation: Acid

Chemical structure of Eosin B

Common Name: Eosin B
Suggested Name: Eosin B
Other Names:

Eosin bluish Imperial red

C.I. Number: 45400
C.I. Name: Acid red 91
Color: Red
Solubility Aqueous: 39%
Solubility Ethanol: 39%
Absorption Maximum: 516-519 (Conn) 514, 395 (Aldrich) 515 (Gurr)
Empirical Formula: C20H6N2O9Br2Na2
Formula Weight: 624


Eosin B is sometimes used instead of Eosin Y ws in staining techniques. It is completely interchangeable, but gives a barely noticeable bluish cast instead of the yellow cast of Eosin Y. It is commonly used to compound Romanowsky stains.

The free radical of this dye, eosinol B, can be made from Eosin B by treatment with hydrochloric acid. It is sometimes called Eosin B, spirit soluble.

Compare the structural formula of some eosin homologs.


  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. Edward Gurr, 1971
    Synthetic dyes in biology, medicine and chemistry
    Academic Press, London, England.
  4. Susan Budavari, Editor,
    The Merck Index, Ed. 12
    Merck & Co., Inc., Whitehouse Station, NJ, USA