Solid-Phase Extraction of Vitamins A and E from Animal Feeds: A Substitute for Liquid–Liquid Extraction

Abstract

Abstract A substitution was developed for the laborious liquid–liquid extraction method according to European Economic Community legislation for isolation of Vitamins A and E from feeds. A rapid method for the isolation of the 2 vitamins by means of solid-phase extraction on OASIS® columns gave reproducible results comparable to those of the European Union-recommended method. The vitamins in the feed were extracted with a minor modification of the official method (KOH in ethanol). After filtration, a portion was applied onto the OASIS column and then washed. The vitamins were eluted in ethyl acetate. The eluate evaporated under nitrogen, and the precipitate was dissolved in methanol before liquid chromatography analysis. Recovery for this method was 80% for Vitamin A and 110% for Vitamin E, as calculated as the result for National Institute of Standards and Technology (NIST) Infant Formula. Day-to-day reproducibility for the method was 21 and 11% of the average results for Vitamins A and E, respectively.