Determination of phylloquinone in vegetables, fruits, and berries by high-performance liquid chromatography with electrochemical detection

The amount of phylloquinone (vitamin K-1) in the most important vegetables, fruits, and berries available in Finland was analyzed by a reversed-phase high-performance liquid chromatographic (HPLC) method. In this method phylloquinone was quantified with a dual-electrode electrochemical (EC) detector using menaquinone 4 (MK-4) as an internal standard. The seasonal variation of phylloquinone in some vegetables was also investigated. The highest phylloquinone content was analyzed in parsley (mean content = 360 mu g/100 g), while other green vegetables were also found to be good sources of phylloquinone (general mean content > 100 mu g/100 g). In contrast, red and yellow vegetables and fruits contained considerably lower amounts of phylloquinone (mean content < 20 mu g/100 g). The mean phylloquinone content of berries ranged from 5.5 mu g/100 g (strawberry) to 30 mu g/100 g (black currant). Variation in the phylloquinone content of vegetables was considerable, although the main reason for this could not be determined. The contribution of vegetables, fruits, and berries to the average daily dietary intake of phylloquinone in Finland was estimated to be approximately 40 mu g.