Tj. Koivu et al., DETERMINATION OF PHYLLOQUINONE IN VEGETABLES, FRUITS, AND BERRIES BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION, Journal of agricultural and food chemistry, 45(12), 1997, pp. 4644-4649
The amount of phylloquinone (vitamin K-1) in the most important vegeta
bles, fruits, and berries available in Finland was analyzed by a rever
sed-phase high-performance liquid chromatographic (HPLC) method. In th
is method phylloquinone was quantified with a dual-electrode electroch
emical (EC) detector using menaquinone 4 (MK-4) as an internal standar
d. The seasonal variation of phylloquinone in some vegetables was also
investigated. The highest phylloquinone content was analyzed in parsl
ey (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 co
ntained 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.