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

A reversed phase high performance liquid chromatographic method is des cribed for the simultaneous determination of nicotinic acid, nicotinam ide, pyridoxine, thiamine, folio acid and riboflavin. The vitamins wer e 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 ea ch vitamin. All vitamins were separated in less than 12 minutes. This method was applied to the determination all the vitamins in multivitam in pharmaceuticals. Recovery studies showed good results for all solut es (93.4%-106.5%) and some day coefficients of variation ranging from 0.91% to 4.95%. Narrow bore columns were recommended because this alte rnative provided a good separation efficiency, plus greater economy an d sensibility. Finally, the performance of an ordinary UV detector and that of a rapid spectral detector in this type of determination were critically compared.