tetrasodium 3,3'-[iminobis[[4-hydroxy-5-[[4-[(4-nitro-2-sulphonatophenyl)amino]phenyl]azo]-2,1-phenylene]azo-4,1-phenyleneimino]]bis[6-nitrobenzenesulphonate]

3,3'-[Iminobis[[4-hydroxy-5-[[4-[[4-nitro-2-[(sodiooxy)sulfonyl]phenyl]amino]phenyl]azo]-2,1-phenylene]azo-4,1-phenyleneimino]]bis(6-nitrobenzenesulfonic acid sodium) salt