2,2'-Biphenyldisulfonic acid, 4,4'-diamino-5,5'-dimethyl- 3,3'-Tolidine-6,6'-disulfonic acid 4,4'-Diamino-5,5'-dimethyl-2,2'-biphenyldisulfonic acid 83-83-0 NSC37128 [1,1'-Biphenyl]-2,2'-disulfonic acid, 4,4'-diamino-5,5'-dimethyl-