61931-83-7 Benzenesulfonic acid, 4-(4,5-dihydro-4-((2-hydroxy-5-methyl-3-nitrophenyl)azo)-3-methyl-5-oxo-1H-pyrazol-1-yl)-, monosodium salt EINECS 263-340-0 Sodium p-(4,5-dihydro-4-((2-hydroxy-5-methyl-3-nitrophenyl)azo)-3-methyl-5-oxo-1H-pyrazol-1-yl)benzenesulphonate