A deep blue dye (with the formula OC6H4NC6H4OH) used to detect AMMONIA in a common test called the Berthelot's reaction and to detect PARACETAMOL by spectrophotometry.

Synonyms: 2,5-Cyclohexadien-1-one, 4-((4-hydroxyphenyl)imino)-, Indophenol, 500-85-6