SIMULTANEOUS ADSORPTIVE STRIPPING VOLTAMMETRIC DETERMINATION OF RIBOFLAVIN AND FOLIC-ACID IN MULTIVITAMIN PREPARATIONS

The adsorptive stripping voltammetric behaviour of folic acid and riboflavin was studied at a hanging mercury drop electrode by phase-selective a.c. voltammetry. In 0.1 M sodium acetate buffer (pH 5.0) a cathodic scan gave peaks at -0.29 and -0.55 V vs. Ag/AgCl for riboflavin and folic acid, respectively. The adsorptive stripping response was evaluated with respect to concentration dependence and preconcentration time. Both compounds can be simultaneous determined with a relative standard deviation of 1.4% at 5 x 10(-8) M riboflavin and 0.74% at 10(-8) M folic acid. The method compared favourably with liquid chromatography with UV detection and was succesfully applied to the simultaneous determination of both compounds in multivitamin preparations. The average contents of riboflavin and folic acid were found to be 15.19 mg +/- 2.1% and 1.8 mg +/- 2.6%, respectively.