1,3-Naphthalenedisulfonic acid, 7,7'-(carbonylbis(imino(2-methyl-4,1-phenylene)azo))bis-, sodium salt 68966-51-8 7,7'-(Carbonylbis(imino(2-methyl-p-phenylene)azo))bis(naphthalene-1,3-disulphonic) acid, sodium salt EINECS 273-440-6