2-Naphthalenesulfonic acid, 7-hydroxy-8-((4-nitrophenyl)azo)- 68959-12-6 7-Hydroxy-8-((4-nitrophenyl)azo)naphthalene-2-sulphonic acid 7-Hydroxy-8-(4-nitrophenyl)azo-2-naphthalenesulfonic acid EINECS 273-397-3