| Abstract: | The application of high-performance liquid chromatography to the determination of vitamin A in animal feeding stuffs has been investigated. Particular emphasis has been given to some of those aspects that would be of importance to official control methods. Vitamin A exists as six geometric isomers, some or all of which may be present in feed extracts. The effect of this on both ultraviolet and fluorescence quantitation is described, using all-trans retinol and 13-cis retinol as examples of the different isomers. The isomers were eluted coincidentally from a reversed-phase column; information on the isomeric composition of the feed extracts was obtained by means of the maleic anhydride reaction. These results were confirmed by a normal phase chromatographic procedure which resolved all-trans and 13-cis retinol. |
