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Chromotrope 2R

Chromotrope 2R

Class: Azo
Ionisation: Acid

Chemical structure of Chromotrope 2R

Common Name: Chromotrope 2R
Suggested Name: Chromotrope 2R
Other Names:

Carmoisine 6R

C.I. Number: 16570
C.I. Name: Acid red 29
Color: Red
Solubility Aqueous: 19.30%
Solubility Ethanol: 19.30%
Absorption Maximum: 503, 542 (Conn) 510, 530 (Aldrich)
Empirical Formula: C16H10N2O8S2Na2
Formula Weight: 468.386


Chromotrope 2R may be used as the plasma stain in trichrome techniques, most notably in Gomori's one-step method. It can replace xylidine ponceau in Masson's trichrome.

It has been suggested as a replacement for eosin Y following nuclear staining with Celestine blue B. One of its most well-known uses is in solution with phenol in Lendrum's method for eosinophil granules.


  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.
    Encyclopaedia of microscopic stains,
    Leonard Hill (Books) Ltd., London, UK.
  4. Floyd J. Green
    Sigma-Aldrich handbook of stains, dyes and indicators,
    Aldrich Chemical Company Inc., Milwaukee, Wisconsin, USA.