tetrasodium 7,7'-(carbonyldiimino)bis[4-hydroxy-3-[(4-sulphonatophenyl)azo]naphthalene-2-sulphonate]

7,7'-(Carbonyldiimino)bis[4-hydroxy-3-[[4-(sodiooxysulfonyl)phenyl]azo]-2-naphthalenesulfonic acid sodium] salt