Synonyms: Quinolinium,2-[(1-ethyl-2(1H)-quinolinylidene)methyl]-1-(4-sulfobutyl)-, hydroxide, innersalt; Quinolinium, 2-[(1-ethyl-2(1H)-quinolylidene)methyl]-1-(4-sulfobutyl)-,hydroxide, inner salt (8CI); 2,2'-Cyanine hydroxide,anhydro-1-ethyl-1'-(4-sulfobutyl)- (8CI);Anhydro-1-ethyl-1'-(4-sulfobutyl)-2,2'-cyanine hydroxide; Anhydro-1-ethyl-1'-sulfobutyl-2,2'-cyaninehydroxide