FRACTIONATION OF THE TRIACYGLYCEROLS OF EVENING PRIMROSE OIL BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY IN THE SILVER ION MODE

Triacylglycerols from evening primrose oil have been resolved by HPLC in the silver ion mode on a stationary phase consisted of an ion exchange medium, i.e. a silica gel matrix with bonded sulphonic acid moieties, loaded with silver ions. The mobile phase was a gradient of acetone into 1,2-dichloroethane-dichloromethane initially, before acetonitrile was introduced. A mass detector was employed to monitor separations. Fractions were collected via a stream-splitter for identification and quantification by gas chromatography as methyl esters. Excellent resolution was obtained, and species differing in saturation from disaturated-monoenoic to monodienoicditrienoic were resolved and quantified.