DETERMINATION OF PHYLLOQUINONE IN OILS, MARGARINES AND BUTTER BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION

A high-performance liquid chromatographic (HPLC) method for the determ ination of phylloquinone in oils and margarines following purification of hexane solutions of oils or hexane extracts of margarines by strai ght-phase semipreparative HPLC is described. Phylloquinone was quantif ied by reverse-phase HPLC with a dual-electrode electrochemical detect or operating in the redox mode. Menaquinone-4 (MK-4) was used as an in ternal standard. By this method the phylloquinone present in the main oils and margarines available on the Finnish market was determined. Th e same method, but without the internal standard, was applied to butte r. The detection limit of phylloquinone was 50 pg per injection, and i ts recovery when added to oil and margarine samples and quantified by the internal standard method was 98% and 102%, respectively. The mean phylloquinone content of oils ranged from 1.5 mu g (refined rapeseed o il) to 0.10 mu g (sunflower oil). In the soft margarines with 80% fat, the phylloquinone levels were 0.89-1.1 mu g g(-1). The phylloquinone content of margarines with 40% and 60% fat correlated with their fat c ontent. Blended and hard margarines contained less phylloquinone than the soft margarines with corresponding fat contents. The contribution of oils and margarines to the average daily dietary intake of phylloqu inone in Finland was estimated to be approximate 40 mu g. (C) 1997 Els evier Science Ltd.