tetrasodium 4,4'-bis[[4,5-dihydro-3-methyl-5-oxo-1-(4-sulphonatophenyl)-1H-pyrazol-4-yl]azo]-5,5'-dimethyl[1,1'-biphenyl]-2,2'-disulphonate

4,4'-Bis[[[4,5-dihydro-3-methyl-5-oxo-1-(4-sodiooxysulfonylphenyl)-1H-pyrazol]-4-yl]azo]-5,5'-dimethyl-1,1'-biphenyl-2,2'-disulfonic acid disodium salt