Synonyms: 1,3’-Bipyridinium,5’-[[4-[[7-[(1’,2’-dihydro-6’-hydroxy-3,4-dimethyl-2’-oxo [1,3’-bipyridinium]-5’-yl)azo]-1-hydroxy-3-sulfo-2-naphthalenyl]azo]phenyl]azo]-1’- [3-(dimethylamino)propyl]-1’,2’-oxo-, salt with 2-hydroxypropanoic acid;1,3’-Bipyridinium, 5’-[[4-[[7-[(1’,2’-dihydro- 6’-hydroxy-3,4’-dimethyl-2’-oxo[1,3’-bipyridinium ]-5’-yl)azo]-1-hydroxy-3-sulfo-2-naphthalenyl]az o]phenyl]azo]-1’-[3-(dimethylamino)propyl]-1’,2’-dihyd ro-6’-hydroxy-4’-methyl-2’-oxo-, salt with 2-hydroxypr