Ponceau 6R, or Crystal ponceau 6R, Crystal scarlet, Brilliant crystal scarlet 6R, Acid Red 44, or C.I. 16250, is a red azo dye. It is soluble in water and slightly soluble in ethanol. It is used as a food dye, with E Number E126. It is also used in Histology, for staining fibrin with the MSB Trichcomb stain. It usually comes as disodium salt.

Synonyms: C.I. 16250; Acid Red 44; Ponceau 6R; Crystal Ponceau 6R; Brilliant Crystal Scarlet

Molecular Formula: C20H12N2Na2O7S2

Molecular Weight: 502.43

Description: Dark brown powder

Melting Point: > 300 Deg. C

Lambda Max: 509-514 nm

Dye content: ~ 80%

Solubility 0.1% (Water): Clear red solution

Loss on drying: <20% at 110 Deg. C/ 1 hour

Not considered harmful under normal laboratory conditions

Cas No: 2766-77-0