C.i.direct red 28; 1-naphthalenesulfonic acid, 3,3'-((1,1'-biphenyl)-4,4'-diylbis(azo))bis(4-amino-, disodium salt; Atlantic congo red; Atul congo red; Azocard red congo; Benzo congo red; Brasilamina congo 4b; Ci 22120; Direct red 28; Ci direct red 28, disodium salt; Congo red; Congo red 4b; Congo red 4bx; Congo red cr; Congo red h; Congo red ici; Congo red l; Congo red m; Congo red n; Congo red r; Congo red rs; Congo red w; Congo red ws; Cotton red 4bc; Cotton red 5b; Cotton red l; Diacotton congo red; Direct red c; Direct red dc cf; Direct red k; Erie congo 4b; Haemomedical; Haemonorm; Hemorrhagyl; Hispamin congo 4b; Kayaku congo red; Mitsui congo red; Peeramine congo red; Sodium diphenyldiazo bis alpha naphthylamine sulfonate; Solucongo; Sugai congo red; Tertrodirect red c; Trisulfon congo red; Vondacel red cl.