Congo red, chemical name: diphenyl-4,4'-bis(azo-2-)-1-aminonaphthalene-4-sulfonic acid sodium, the molecular formula is C32H22N6Na2O6S2, which is a brown-red powder, soluble in water and yellow Red, soluble in alcohol and orange. Used as an acid-base indicator, the color change range is 3.5 to 5.2, the alkali state is red, and the acid state is blue-violet. Also used to diagnose amyloid lesions.

Function:
Acid-base indicator, pH 3.0 (blue-violet) ~ 5.0 (red); detection of hydrochloric acid and paper acidity in gastric juice; determination of boric acid, cyanide; biological media additives; biological staining, such as embryonic sections, plant mucin, fiber Coloring, elastic tissue, etc.