disodium p-[4,5-dihydro-4-[[4-methoxy-3-[[2-(sulphonatooxy)ethyl]sulphonyl]phenyl]azo]-3-methyl-5-oxo-1H-pyrazol-1-yl]benzenesulphonate

4-[[4,5-Dihydro-4-[[4-methoxy-3-[[2-(sulfooxy)ethyl]sulfonyl]phenyl]azo]-3-methyl-5-oxo-1H-pyrazol]-1-yl]benzenesulfonic acid disodium salt