2,7-Naphthalenedisulfonic acid,5-(acetylamino)-3-[[6-[[4-[[4-[[6-[[8-(acetylamino)-1-hydroxy-3,6-disulfo-2-naphthalenyl]azo]-1-hydroxy-3-sulfo-2-naphthalenyl]azo]benzoyl]amino]phenyl]azo]-5-hydroxy-7-sulfo-2-naphthalenyl]azo]-4-hydroxy-,hexaammonium salt