FREMGANGSMAADE TIL RENSNING AF RIBOFLAVIN

Very pure riboflavin (I) is obtained by a process in which the riboflavin is dissolved in dilute aqueous alkali metal hydroxide solution, if necessary the alkaline solution is purified by treatment with active carbon or with a solvent which is insoluble or only slightly soluble in water, the resulting alkaline solution of I is introduced into water which is at 90 DEG -100 DEG C. and to which an acid has been added in an amount such that the reaction mixture is brought to a pH of from 6.5 to 0.8, the temperature being maintained at from 40 DEG to 100 DEG C., the reaction mixture is kept at from 90 DEG to 100 DEG C. for from 10 to 80 minutes and cooled, and I is then isolated.