1,2,4-Benzenetrisulfonic acid,5-[[[4,5-dihydro-4-[3-[5-hydroxy-1-methyl-3-[[(2,4,5-trisulfophenyl)amino]carbonyl]-1H-pyrazol-4-yl]-2-propenylidene]-1-methyl-5-oxo-1H-pyrazol-3-yl]carbonyl]amino]-, hexapotassium salt