trisodium 4-[[4-[[(3,6-dichloropyridazin-4-yl)carbonyl]amino]-2-sulphonatophenyl]azo]-4,5-dihydro-5-oxo-1-(4-sulphonatophenyl)-1H-pyrazole-3-carboxylate

4-[[4-[[(3,6-Dichloropyridazin-4-yl)carbonyl]amino]-2-(sodiosulfo)phenyl]azo]-4,5-dihydro-5-oxo-1-[4-(sodiosulfo)phenyl]-1H-pyrazole-3-carboxylic acid sodium salt