Congo red

Congo red

noun \ˌkäŋ-(ˌ)gō-ˈred\

Definition of CONGO RED

: an azo dye C₃₂H₂₂N₆Na₂O₆S₂ that is red in alkaline and blue in acid solution and that is used in a number of diagnostic tests and especially for the detection of amyloidosis since the injected dye tends to be retained by abnormal amyloid deposits