Reaction between Riboflavin and Sulfuric Acid: Formation and Characterization of Riboflavin Polysulfates

When riboflavin was dissolved in concd. H2SO4, it was quantitatively transformed into sulfated riboflavins without any polymerization or degradation. The sulfated riboflavins were separated by ion-exchange chromatography into four components which were identified to riboflavin mono-, di-, tri-, and tetrasulfates, respectively. The results of periodate oxidation revealed that the riboflavin mono-and disulfates were rather complex in their compositions. The influence of reaction conditions on the sulfation of riboflavin was examined. It was found that both the temperature and time of reaction did not so much affect the sulfation, but the temperature of ether used for separating products from concd. H2SO4, did decisively.