Evaluation of an HPLC method for the determination of phylloquinone (vitamin K1) in various food matrixes

The amount of phylloquinone (vitamin K 1 ) in five different foods was determined by applying a highly sensitive HPLC method that incorporates postcolumn chemical reduction of the quinone followed by fluorescence detection of the hydroquinone form of the vitamin. After initial extraction in 2-propanol and hexane, the food extracts were purified by solid-phase extraction (SPE) on silica gel and analyzed by HPLC or, depending on the matrix, further purified using liquid-phase reductive extraction or reversed-phase SPE on C 18