2,7-Naphthalenedisulfonic acid, 6-((4-amino-2-hydroxyphenyl)azo)-3-((4'-((7-((4-amino-2-hydroxyphenyl)azo)-1-hydroxy-3-sulfo-2-naphthalenyl)azo)-3,3'-dimethyl(1,1'-biphenyl)-4-yl)azo)-4-hydroxy-, trisodium salt 72845-86-4