Comparison of Emmerie-Engel Method and Gas Chromatographic Method for Determination of Supplemental α-Tocopheryl Acetate in Feed Concentrates
Abstract The determination of supplemental a-tocopheryl acetate in high potency vitamin E powders and oils was compared using the Emmerie- Engel method and gas chromatography (GC). The Emmerie-Engel reaction requires saponification, extraction of the saponiflable fracaon, and quantitation by colorimetry. GC analysis requires only an extraction and/or dilution before quantitation. These are represented essentially by AOAC methods 43.147-43.151 (colorimetry) and 43.152-43.159 (GC) for high potency vitamin E concentrates. Each method was statistically evaluated for precision and sample-to-sample reproducibility. Each Emmerie-Engel value was divided by the GC value obtained for the same sample; an average of 1.049 with a coefficient of variation of 2.89% was obtained. It was concluded that (he GC procedure was superior to the Emmerie-Engel method, and ahould be the official procedure for determination of supplemental a-tocopheryl acetate in feed concentrates.