PHOTOCHEMICAL SPECTROPHOTOMETRIC DETERMINATION OF RIBOFLAVIN AND RIBOFLAVIN 5'-PHOSPHATE BY MANUAL AND FLOW-INJECTION METHODS

The sensitizing effect of riboflavin (RF) and riboflavin 5'-phosphate (FMN) on the photo-oxidation of dianisidine was studied. The rate of the photochemical reaction was monitored spectrophotometrically at 460 nm. The method allows the determination of RF and FMN in the range 1 X 10(-7)-5 x 10(-6) mol dm(-3) with a relative standard deviation of about 0.68%. The method can be successfully adapted to flow injection. Manual and flow injection methods were satisfactorily applied to the determination of RF or FMN in fortified breads and pharmaceutical preparations. A possible mechanism for the sensitized photoreaction is proposed.