Synonyms: 1,3-Naphthalenedisulfonic acid, 7,7'-(carbonylbis(imino(2-methyl-4,1-phenylene)-2,1-diazenediyl))bis-, sodium salt (1:?);1,3-Naphthalenedisulfonic acid, 7,7'-(carbonylbis(imino(2-methyl-4,1-phenylene)azo))bis-, sodium salt;7,7'-(Carbonylbis(imino(2-methyl-p-phenylene)azo))bis(naphthalene-1,3-disulphonic) acid, sodium salt;sodium 7-[(E)-{4-[({4-[(E)-(6,8-disulfonaphthalen-2-yl)diazenyl]-3-methylphenyl}carbamoyl)amino]-2-methylphenyl}diazenyl]-3-sulfonaphthalene-1-sulfonate