1,5-Naphthalenedisulfonic acid, 3,3'-(carbonylbis(imino(5-methoxy-2-methyl-4,1-phenylene)azo))bis-, tetrasodium salt 6420-33-3 EINECS 229-158-0 Tetrasodium 3,3'-(carbonylbis(imino(5-methoxy-2-methyl-4,1-phenylene)azo))bis(naphthalene-1,5-disulphonate)