An Interlaboratory-Verified Method for the Determination of Vitamins Aand E inMilk- and Soy-Based Infant Formula by Liquid Chromatography with Matrix Solid-Phase Dispersion Extraction
Abstract:An interlaboratory-verified, liquid chromatographic (LC) method is presented for determination of all-racemic α-tocopheryl acetate and retinyl palmitate in infant formula. The extraction procedure uses matrix solid-phase dispersion. A sample is mixed with C18, and the mixture is packed into a reservoir and eluted with selective solvents to extract the analytes. After evaporation and filtration, the sample extract is injected directly into a normal-phase LC system with fluorescence detection. All-racemic α-tocopheryl acetate and retinyl palmitate are quantitated isocratically with a mobile phase of hexane containing isopropanol at 0.2% (v/v) and 0.125% (v/v), respectively. A nonfortified zero control reference material (ZRM) was spiked at 5 levels, with 5 replicate analyses of 1/2x, x, 2x, 4x, and 16x where “x” represents the minimum levels of 250 IU/100 kcal (vitamin A) and 0.7 IU/100 kcal (vitamin E) as specified in Title 21 of the Code of Federal Regulations, part 107.100. Recoveries of retinyl palmitate ranged from 83.8 to 107%, and those of all-racemic α-tocopheryl acetate ranged from 87.7 to 108%. Two additional laboratories analyzed the ZRM samples at 4 spiking levels with 6 replicates. Recoveries of retinyl palmitate and all-racemic α-tocopheryl acetate ranged from 92.2 to 104% and from 91.7 to 101%, respectively, in the second laboratory. Recoveries of retinyl palmitate and all-racemic α-tocopheryl acetate ranged from 85.3 to 97.0% and from 86.6 to 110%, respectively, in the third laboratory. Relative standard deviations for all 3 laboratories ranged from 0.2 to 7.5% with an average of 2.9%. In addition, each laboratory analyzed a commercial milk- and commercial soy-based infant formula. Excellent agreement in results was obtained between the 3 laboratories for vitamins A and E in all matrixes.
Document Type: Research Article
Affiliations: 1: U.S. Food and Drug Administration, Atlanta Center for Nutrient Analysis, 60 Eighth St, Atlanta, GA 30602; Current address: U.S. Food and Drug Administration, Pacific Regional Laboratory Northwest, 22201 23rd Dr SE, Bothell, WA 98026;, Email: William.firstname.lastname@example.org. 2: University of Georgia, Department of Food Science and Technology, Athens, GA 30309. 3: U.S. Food and Drug Administration, Atlanta Center for Nutrient Analysis, 60 Eighth St, Atlanta, GA 30309; Current address: IHO Consulting, 764 Wilkes Dr, Loganville, GA 30052. 4: University of Georgia, Department of Food Science and Technology, Athens, GA 30602. 5: U.S. Food and Drug Administration, Atlanta Center for Nutrient Analysis, 60 Eighth St, Atlanta, GA, 30309.
Publication date: September 1, 2004
- The Journal of AOAC INTERNATIONAL publishes refereed papers and reviews in the fields of chemical, biological and toxicological analytical chemistry for the purpose of showcasing the most precise, accurate and sensitive methods for analysis of foods, food additives, supplements and contaminants, cosmetics, drugs, toxins, hazardous substances, pesticides, feeds, fertilizers and the environment available at that point in time. The scope of the Journal includes unpublished original research describing new analytical methods, techniques and applications; improved approaches to sampling, both in the field and the laboratory; better methods of preparing samples for analysis; collaborative studies substantiating the performance of a given method; statistical techniques for evaluating data. The Journal will also publish other articles of general interest to its audience, e.g., technical communications; cautionary notes; comments on techniques, apparatus, and reagents.
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