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Xylidine Ponceau

Xylidine Ponceau

Class: Azo
Ionisation: Acid

Chemical structure of Xylidine Ponceau

Common Name: Xylidine ponceau
Suggested Name: Xylidine ponceau
Other Names:

Ponceau de xylidine Ponceau 2R

C.I. Number: 16150
C.I. Name: Acid red 26
Color: Red
Solubility Aqueous: Readily
Solubility Ethanol: Readily
Absorption Maximum: 499 (Conn), 502 (Gurr) 503, 388 (Aldrich)
Empirical Formula: C18H14N2O7S2Na2
Formula Weight: 480.44


Masson specified a dye he called Ponceau de xylidine for a variant of his trichrome staining method. Although this dye has not been absolutely identified as the dye he used, it is almost certainly the one, and is accepted as such by general consensus. Its use is largely confined to Masson's trichrome, where it gives a slight orange shading to the red of the cytoplasmic structures.


  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.