Simultaneous determination of ingredients in a vitamin-enriched drink by micellar electrokinetic chromatography.

Micellar electrokinetic chromatography was used to simultaneously determine six active ingredients (2-aminoethanesulfonic acid, nicotinamide, pyridoxine hydrochloride, anhydrous caffeine, riboflavin sodium phosphate and thiamine nitrate) in a vitamin-enriched drink. All the active ingredients and the formulation excipients were successfully separated by micellar electrokinetic chromatography with 135 mM sodium dodecyl sulfate, and were subsequently detected using a diode-array detector operating at 210 nm. The peak shape of pyridoxine hydrochloride was improved by use of sodium tetraborate solution as sample solvent. Sample and standard solutions were stable for at least 24 h in a light-resistant container at room temperature. The established method was validated and demonstrated to be applicable to the determination of the active ingredients in a vitamin-enriched drink. Good linearities were obtained, with correlation coefficients above 0.999. Recoveries and precisions ranged from 99.0 to 101.2%, and from 0.4 to 2.5% RSD, respectively. The detection limit for ingredients ranged from 0.3 to 125 microg ml(-1). These results suggest that micellar electrokinetic chromatography can be used for the determination of ingredients in vitamin-enriched drinks.