2,7-Naphthalenedisulfonic acid, 4-[[2,4-dihydroxy(hydroxymethyl)phenyl]azo]-5-hydroxy-, coupled with diazotized 2-[(4-aminophenyl)amino]-5-nitrobenzenesulfonic acid monosodium salt

2,7-Naphthalenedisulfonic acid, 4-[[2,4-dihydroxy (hydroxymethyl)phenyl]azo]-5-hydroxy-, coupled with diazotized 2-[(4-aminophenyl)amino]-5-nitrobenzenesulfonic acid monosodium salt