4'-[3-Amino-4-(5-sulfo-1-naphtylazo)phenylazo]-4-nitrostilbene-2,2'-disulfonic acid trisodium salt

trisodium 5-[[2-amino-4-[[4-[2-(4-nitro-2-sulphonatophenyl)vinyl]-3-sulphonatophenyl]azo]phenyl]azo]naphthalene-1-sulphonate