5-[[4-[(4-Sulfophenyl)azo]phenyl]-onn-azoxy]-2-[2-[2-sulfo-4-[[4-[(4-sulfophenyl)-onn-azoxy]phenyl]azo]phenyl]ethenyl]benzenesulfonic acid tetrasodium salt
5-[[4-[(4-Sulfophenyl)azo]phenyl]-onn-azoxy]-2-[2-[2-sulfo-4-[[4-[(4-sulfophenyl)-onn-azoxy]phenyl]azo]phenyl]ethenyl]benzenesulfonic acid tetrasodium salt