Synonyms: 1',2'-dihydro-6'-hydroxy-4'-methyl-2'-oxo-5'-(phenylazo)-1,3'-bipyridinium malate;1,3'-Bipyridinium, 1',2'-dihydro-6'-hydroxy-4'-methyl-2'-oxo-5'-(2-phenyldiazenyl)-, 2-hydroxybutanedioate (1:1);1,3'-Bipyridinium, 1',2'-dihydro-6'-hydroxy-4'-methyl-2'-oxo-5'-(phenylazo)-, malate;1,3'-Bipyridinium, 1',2'-dihydro-6'-hydroxy-4'-methyl-2'-oxo-5'-(phenylazo)-, salt with hydroxybutanedioic acid (1:1);Einecs 269-301-4