The ultra-violet absorption of riboflavine

Studies on the biosynthesis of riboflavin. Nitrogen metabolism and flavinogenesis in Eremothecium ashbyii

“…By comparing this value with the El % (445 m,u.) value for pure riboflavin (301; Adamson, 1948), the amount ofriboflavin in the medium could easily be calculated. This procedure was justified for a number of reasons: (a) the starting medium exhibited almost negligible absorption at 445 m,., (b) the absorption spectra of different specimens of riboflavincontaining media were not significantly different from that of pure riboflavin, and (c) paper chromatography of the medium according to the method of Crammer (1948) for riboflavin and its derivatives showed that the pigment was almost entirely riboflavin; apart from riboflavin there only existed minute traces of a spot with blue fluorescence in u.v.…”