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Safranin O

Safranin O

Class: Safranin
Ionisation: Basic

Common Name: Safranin
Suggested Name: Safranin O
Other Names:

C.I. Number: 50240
C.I. Name: Basic red 2
Color: Red
Solubility Aqueous: 5.45%
Solubility Ethanol: 5.45%
Absorption Maximum: 530 (Conn, Aldrich) 517 (Gurr)
Empirical Formula: C20H19N4Cl (Dimethyl) C21H21N4Cl (Trimethyl)
Formula Weight: 350.8 (Dimethyl) 364.9 (Trimethyl)


Safranin O is a mixture of the two compounds shown, according to Conn. Aldrich and Gurr give only the dimethyl compound.

Safranin O is commonly used for staining Gram negative bacteria red in smears to contrast with the blue Gram positive organisms. For tissue sections it is useful as a red nuclear counterstain, and was popular at one time for staining cartilage metachromatically yellow, against red nuclei on a pink background.


  1. R. D. Lillie.
    Conn’s Biological Stains
    Williams & Wilkins, Baltimore, MD., U.S.A.
  2. Edward Gurr, 1971
    Synthetic dyes in biology, medicine and chemistry
    Academic Press, London, England.
  3. Aldrich chemical catalogue, 1992
    Aldrich Chemical Company, Milwaukee, WI, USA.