Also Called: 2,7-Naphthalenedisulfonic acid, 4-amino-3-[[4'-[(2,4-diaminophenyl) azo]-2,2'-disulfo[1,1'-biphenyl]-4-yl]azo ]-5-hydroxy-, sodium salt;2,7-Naphthalenedisulfonic acid, 4-amino-3-[[4'-[(2,4-diaminophenyl)azo]-2,2'-disulfo[1,1'-biphenyl]-4-yl]azo]-5-hydroxy-, sodium salt