Liquid chromatographic analysis of all-trans-retinyl palmitate, beta-carotene, and vitamin E in fortified foods and the extraction of encapsulated and nonencapsulated retinyl palmitate

A liquid chromatographic method is described for the analysis of natural vi tamin E homologues, all-rac-alpha-tocopheryl acetate, retinyl palmitate (en capsulated and nonencapsulated), and beta-carotene in various fortified foo ds. The vitamins are extracted in 2-propanol and hexane without saponificat ion and quantitated by normal phase chromatography with fluorescence and vi sible detection. The sample components were identified using an on-line thr ee-dimensional photodiode array detector, which permitted profiling of the 190-800 nm absorption spectrum of any chromatographic peak. The method show ed linearity for the analytes in their respective calibration ranges. The p ercent recoveries for retinyl palmitate using starch- and gelatin-encapsula ted standards were 101.0 +/- 1.0 and 100.1 +/- 0.9, respectively. The metho d measures six or more analytes in a single injection and differentiates be tween natural and synthetic forms of vitamin E.