Liquid Chromatographic Method for Analysis of AU-rac-α-Tocopheryl Acetate and Retinyl Palmitate in Soy-Based Infant Formula Using a Zero-Control Reference Material (ZRM) as a Method Development Tool

Abstract

A liquid chromatographic method is described for analysis of all-rac-α-tocopheryl acetate, tocopherols, and retinyl palmitate in soy-based infant formula. The vitamins are extracted in isopropyl alcohol and hexane-ethyl acetate without saponification and quantitated by normal-phase chromatography with fluorescence detection. All-rac-α-tocopheryl acetate and retinyl palmitate are quantitated isocratically with mobile phases of 0.5% (v/v) and 0.125% (v/v) isopropyl alcohol in hexane, respectively. Recoveries from zero control reference material soy-based formula averaged 97.2% (n = 25) for retinyl palmitate and 100% (n = 25) for all-rac-α-tocopheryl acetate. Coefficients of variation ranged from 1.21 to 2.86% for retinyl palmitate and from 1.49 to 5.16% for all-rac-α-tocopheryl acetate. The method provides a rapid, specific, and easily controlled assay for analysis of vitamin A and vitamin E in fortified infant formula. Additionally, the method eliminates use of chlorinated solvents.