title: Interlaboratory verified liquid chromatographic method for analysis of vitamins A and E in soy-based infant formula powder.
abstract: An interlaboratory verified, liquid chromatographic (LC) method is presented for the analysis of all-rac-alpha-tocopheryl acetate and retinyl palmitate in soy-based infant formula. The extraction procedure uses sample dehydration with magnesium sulfate followed by extraction with isopropanol, hexane-ethyl acetate (85 + 15, v/v). After evaporation and filtration, the sample extract is injected directly onto a normal-phase LC system with fluorescence detection. All-rac-alpha-tocopheryl acetate and retinyl palmitate are quantitated isocratically with a mobile phase of hexane containing 0.50% (v/v) and 0.125% (v/v) isopropanol, respectively. A zero control reference material (ZRM) was spiked at 5 levels, with 5 replicate analyses of 1/2x, x, 2x, 4x, and 16x where "x" is the minimum level of 250 IU/100 kcal (vitamin A) and 0.7 IU/100 kcal (vitamin E) as specified in 21 Code of Federal Regulations 107.100. The following recoveries and RSD values represent an average (n = 25) of the 5 levels for each analyte: all-rac-alpha-tocopheryl acetate, 100% (RSD = 3.5%); retinyl palmitate, 97.2% (RSD = 2.1%). Two additional laboratories analyzed the fortified ZRM samples. Average recoveries (n = 24) of all-rac-alpha-tocopheryl acetate and retinyl palmitate at 4 levels were all-rac-alpha-tocopheryl acetate, 99.0% (RSD = 4.0%), and retinyl palmitate, 96.2% (RSD = 1.4%) at the second laboratory. Average recoveries (n = 24) of all-rac-alpha-tocopheryl acetate and retinyl palmitate at 4 levels were all-rac-alpha-tocopheryl acetate, 102% (RSD = 1.4%) and retinyl palmitate, 95.7% (RSD = 2.0%) at the third laboratory. In addition, 6 replicates of the same commercial soy-based infant formula powder were run by the 3 laboratories.
authors.affiliation: US Food and Drug Administration, Atlanta Center for Nutrient Analysis, Atlanta, GA 30309, USA. wchase@ora.fda.gov
authors.forename: G William
authors.initials: GW
authors.lastname: Chase
authors.forename: Lin
authors.initials: L
authors.lastname: Ye
authors.forename: Vicky C
authors.initials: VC
authors.lastname: Stoakes
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Eitenmiller
authors.forename: Austin R
authors.initials: AR
authors.lastname: Long
mesh_terms: D000465:Algorithms; D000975:Antioxidants / Q000032:analysis*; D002853:Chromatography, Liquid; D006801:Humans; D007202:Indicators and Reagents; D007223:Infant; D007225:Infant Food / Q000032:analysis*; D012015:Reference Standards; D015203:Reproducibility of Results; D013025:Glycine max / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D014801:Vitamin A / Q000032:analysis*; D014810:Vitamin E / Q000032:analysis*
chemical_list: D000975:Antioxidants; D007202:Indicators and Reagents; D014801:Vitamin A; D014810:Vitamin E