Synonyms: Calcium 4,4'-bis((1-(((2,4-dimethylphenyl)amino)carbonyl)-2-oxopropyl)azo)(1,1'-biphenyl)-2,2'-disulphonate;(1,1'-Biphenyl)-2,2'-disulfonic acid, 4,4'-bis((1-(((2,4-dimethylphenyl)amino)carbonyl)-2-oxopropyl)azo)-, calcium salt;calcium 5-[1-[(2,4-dimethylphenyl)carbamoyl]-2-oxo-propyl]azo-2-[4-[1-[(2,4-dimethylphenyl)carbamoyl]-2-oxo-propyl]azo-2-sulfonato-phenyl]benzenesulfonate