Synonyms: 1,3,3-Trimethyl-2-((methyl(4-(phenylazo)phenyl)hydrazono)methyl)-3H-indolium sulphate (2:1);3H-Indolium, 1,3,3-trimethyl-2-((methyl(4-(phenylazo)phenyl)hydrazono)methyl)-, sulfate (2:1);N-methyl-4-phenylazo-N-[(1,3,3-trimethylindol-1-ium-2-yl)methyleneamino]aniline sulfate