12220-23-4 12227-66-6 15792-43-5 2,7-Naphthalenedisulfonic acid, 5-(acetylamino)-3-((4-dodecylphenyl)azo)-4-hydroxy-, disodium salt C.I. Acid Red 138 Disodium 5-(acetylamino)-3-((4-dodecylphenyl)azo)-4-hydroxynaphthalene-2,7-disulphonate EINECS 239-893-9