tetrasodium 4,4'-bis[[5-[[5-(aminosulphonyl)-2-hydroxyphenyl]azo]-1-hydroxy-6-(phenylamino)-3-sulphonato-2-naphthyl]azo][1,1'-biphenyl]-3,3'-dicarboxylate

4,4'-Bis[[5-[[5-(aminosulfonyl)-2-hydroxyphenyl]azo]-1-hydroxy-6-(phenylamino)-3-sulfo-2-naphtyl]azo]-1,1'-biphenyl-3,3'-dicarboxylic acid tetrasodium salt