2-Naphthalenesulfonic acid, 5,5'-[(3,3'-dimethyl[1,1'-biphenyl]-4,4'-diyl)bis(azo)]bis[6-amino-, disodium salt 6406-01-5 Benzopurpurine B C.I. 23560 C.I. Direct Red 21 C.I. Direct Red 21, disodium salt Hispamin Red B NSC242027