Auramine O is a hydrochloride obtained by combining 4,4'-carbonimidoylbis(N,N-dimethylaniline) with one molar equivalent of hydrogen chloride. It is yellow flakes or powder.
Auramine O (C.I. 41000) is a dry dye for fluorescence and can be used for the staining of Mycobacteria in smears and sections of human origin. The mechanism is a non-specific binding of fluorescence dye on a substrate.