1-Naphthalenesulfonic acid, 4-((2,4-dihydroxy-5-((7-sulfo-1-naphthalenyl)azo)phenyl)azo)-, disodium salt 4-((5-((7-Sulfonaphthalene-1-yl)azo)-2,4-dihydroxyphenyl)azo)-1-naphthalenesulfonic acid, disodium salt 75627-16-6