23807-34-3 4-(2-((4-((2-Hydroxyethyl)sulfonyl)-6-methoxy-m-tolyl)azo)acetoacetamido)-5-methoxy-o-toluenesulfonic acid, hydrogen sulfate (ester) Benzenesulfonic acid, 5-methoxy-4-((2-((2-methoxy-5-methyl-4-((2-(sulfooxy)ethyl)sulfonyl)phenyl)azo)-1,3-dioxobutyl)amino)-2-methyl-