A red-brown azo dye that becomes blue in acidic conditions, used as a chemical indicator and as a stain in histology.
More example sentences
- The chemicals used in making Congo red and the other aniline dyes were primarily derived from the coal-tar waste products of the coal gas and steel industries in Germany's Ruhr Valley.
- The presence of amyloid confirmed histologically by either Congo red or sulfonated Alcian blue stains or by electron microscopy was seen in 8 muscles.
- Potassium permanganate incubation caused loss of reactivity with Congo red.
Definition of Congo red in:
- The British & World English dictionary