2,7-Naphthalenedisulfonic acid, 4-amino-3,6-(bis(4-nitrophenyl)azo)-5-hydroxy-, disodium salt 2,7-Naphthalenedisulfonic acid, 4-amino-5-hydroxy-3,6-bis((4-nitrophenyl)azo)-, disodium salt 68084-24-2