LIQUID-CHROMATOGRAPHIC METHOD FOR ANALYSIS OF ALL-RAC-ALPHA-TOCOPHERYL ACETATE AND RETINYL PALMITATE IN MILK-BASED INFANT FORMULA USING MATRIX SOLID-PHASE DISPERSION

A liquid chromatographic method is described for analysis of all-rac-a lpha-tocopheryl acetate, tocopherols, and retinyl palmitate in milk-ba sed infant formula. The vitamins are extracted from infant formula wit hout saponification by matrix solid-phase dispersion and quantitated b y normal-phase chromatography with fluorescence detection. Retinyl pal mitate and vitamin E are quantitated isocratically with mobile phases of 0.125% (v/v) and 0.5% (v/v) isopropyl alcohol in hexane, respective ly Results were similar to the certified and non-certified ranges for all-rac-alpha-tocopheryl acetate, retinyl palmitate, and tocopherols i n the infant formula standard reference material (SRM) 1846. Results a lso compared favorably with the label declaration on a retail infant f ormula. Recoveries were determined on an analyte-fortified zero contro l reference material for milk-based infant formula and averaged 96.8% (n = 30) for retinyl palmitate and 91.5% (n = 25) for all-rac-alpha-to copheryl acetate. Examination of 5 concentrations for each analyte gav e results that were linear (r = 0.999) over the concentration examined , with coefficients of variation ranging from 1.02 to 5.86%. The metho d provides a rapid, specific, and easily controlled assay for analysis of retinyl palmitate and vitamin E in fortified infant formula. Addit ionally, the method minimizes solvent use by using only 14 mL solvent per extraction.