DETERMINATION OF WATER-SOLUBLE VITAMINS BY LIQUID-CHROMATOGRAPHY WITH ORDINARY AND NARROW-BORE COLUMNS

A reversed phase high performance liquid chromatographic method is described for the simultaneous determination of nicotinic acid, nicotinamide, pyridoxine, thiamine, folio acid and riboflavin. The vitamins were separated on a C-8 bonded phase column and eluted with a dihidrogen phosfate buffer, hexanesulphonate and methanol as the eluent. A rapid spectral detector Diode Array was used to optimise the detection of each vitamin. All vitamins were separated in less than 12 minutes. This method was applied to the determination all the vitamins in multivitamin pharmaceuticals. Recovery studies showed good results for all solutes (93.4%-106.5%) and some day coefficients of variation ranging from 0.91% to 4.95%. Narrow bore columns were recommended because this alternative provided a good separation efficiency, plus greater economy and sensibility. Finally, the performance of an ordinary UV detector and that of a rapid spectral detector in this type of determination were critically compared.