CUPRATE(3-),[.MU.-[7-[[4'-[[8-(ACETYLAMINO)-1-(HYDROXY-.KAPPA.O)-3-SULFO-2-NAPHTHALENYL]AZO-.KAPPA.N1]-3,3'-DI(HYDROXY-.KAPPA.O)[1,1'-BIPHENYL]-4-YL]AZO-.KAPPA.N1]-8-(HYDROXY-.KAPPA.O)-1,6-NAPHTHALENEDISULFONATO(7-)]]DI-,TRISODIUM