4-[[2,4-dihydroxy-3-[(4-nitrophenyl)azo]-5-[[4-(phenylamino)-3-sulphophenyl]azo]phenyl]azo]-5-hydroxynaphthalene-2,7-disulphonic acid, sodium salt

4-[[2,4-Dihydroxy-3-[(4-nitrophenyl)azo]-5-[[4-(phenylamino)-3-sulfophenyl]azo]phenyl]azo]-5-hydroxy-2,7-naphthalenedisulfonic acid/sodium,(1:x) salt