Ponceau S.

Structural formula
CI Acid Red 112 as a free acid
General
Surname	Ponceau S.
other names	Tetrasodium 3-hydroxy-4 - ({2-sulfonato-4 - [(4-sulfonatophenyl) diazenyl] phenyl} diazenyl) -2,7-naphthalene disulfonate ( IUPAC ) CI Acid Red 112 CI 27195
Molecular formula	C 22 H 12 N 4 Na 4 O 13 S 4
External identifiers / databases
CAS number 6226-79-5 EC number 228-319-2 ECHA InfoCard 100.025.745 PubChem 2723873 ChemSpider 17967085 Wikidata Q2103492
properties
Molar mass	760.57 g mol −1 (672.64 g mol −1 , free acid)
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 315-319-335 P: 261-305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Ponceau S is a red bisazo dye from the application group of acid dyes , which is often used to reversibly stain proteins on a nitrocellulose or PVDF membrane.

use

In Western blotting , the dye is used to check whether protein has been transferred to the membrane . Ponceau S binds reversibly to the positively charged amino groups of the proteins. A Ponceau-S stain is very easy to wash out with water to remove the membrane e.g. B. to continue to be used for immunodetection with antibodies .

A widely used recipe for coloring is 0.1% Ponceau S in 5% acetic acid or 2% Ponceau S in 30% trichloroacetic acid and 30% 5-sulfosalicylic acid (2-hydroxy-5-sulfobenzoic acid).

Individual evidence

1. ↑ ^{a b} Datasheet Ponceau S from Sigma-Aldrich , accessed on April 21, 2011 ( PDF ).