Benzenesulfonic acid,4-[[[4,5-dihydro-1-(2-hydroxyethyl)-4-[5-[5-hydroxy-1-(2-hydroxyethyl)-3-[[(4-sulfophenyl)amino]carbonyl]-1H-pyrazol-4-yl]-2,4-pentadienylidene]-5-oxo-1H-pyrazol-3-yl]carbonyl]amino]-, dipotassium salt