Determination of B2 vitamers in pharmaceutical preparations, foods and animal tissues by a photokinetic method

Abstract

A fast and sensitive photokinetic method for the determination of riboflavin (RF) and riboflavin 5′-phosphate (FMN) is described. It is based on the rate of photoreduction of RF and FMN by EDTA in the absence of oxygen. The rate of photoreduction is a linear function of the concentration of both B₂ vitamers at very low concentrations.

The rate of these photochemical reactions is monitored polarographically by recording the limiting current of p-benzoquinone, which is reduced by the 1,5-dihydro forms of RF and FMN that are generated in the photochemical reactions. The results obtained by the application of the fixed time, fixed concentration and initial rate kinetic methods have been evaluated. An alternative method for monitoring the rate of the process is by measuring the time necessary for the total reduction of p-benzoquinone. The end-point is detected with two platinum electrodes at an applied voltage of 100 mV. The procedure has been successfully applied to the determination of B₂ vitamers in pharmaceuticals, foods and animal tissues.