Synonyms: tetrasodium 4,4’-bis[[4,5-dihydro-3-methyl-5-oxo-1-(4-sulphonatophenyl)-1H-pyrazol-4-yl]azo][1,1’-biphenyl]-2,2’-disulphonate;[1,1’-Biphenyl]-2,2’-disulfonic acid, 4,4’-bis[[4,5-dihydro-3-methyl-5-oxo-1-(4-sulfophenyl)-1H-pyrazol-4-yl]azo]-, tetrasodium salt;[1,1’-Biphenyl]-2,2’-disulfonic acid,4,4’-bis[[4,5-dihydro-3-methyl-5-oxo-1-(4’-sulfophenyl)-1H-pyrazol-4-yl]azo]-, tetrasodium salt