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Sudan III

Sudan III

Class: Azo
Ionisation: Lysochrome

Chemical structure of Sudan III

Common Name: Sudan III
Suggested Name: Sudan III
Other Names:

Sudan red BK

C.I. Number: 26100
C.I. Name: Solvent red 23
Color: Red
Solubility Aqueous: Insoluble
Solubility Ethanol: Insoluble
Absorption Maximum: 508-510 (Conn) 507, 354 (Aldrich) 503 (Gurr)
Empirical Formula: C22H16N4O
Formula Weight: 352.4


Sudan III is a lysochrome (fat soluble dye) predominantly used for demonstrating triglycerides in frozen sections, but it may also stain some protein bound lipids in paraffin sections. It is less popular than oil red O as it has a more orange shade.

Compare this dye to the other common lysochromes sudan IV, oil red O and sudan black B.


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