Determination of phylloquinone and menaquinones in animal products with fluorescence detection after postcolumn reduction with metallic zinc

A high-performance liquid chromatographic (HPLC) method for the determinati on of phylloquinone and menaquinones in foods of animal origin is described . The K vitamers were quantified with a fluorescence detector after postcol umn reduction with metallic zinc using K-1(25) as an internal standard. Ext raction was done either with 2-propanol-hexane (meat and fish products) or with acid hydrolysis method (dairy products). Prior to quantification, samp le extracts were purified by semipreparative HPLC; in addition, the fats of cheese and rainbow trout samples were removed with lipase hydrolysis. By t his method the phylloquinone and menaquinones (MK-4 to MK-10) present in a few representative samples of different animal food groups were determined. HPLC-MS was used to confirm the identification of K vitamers. Long-chain m enaquinones were found from bovine and pig livers as well as from various c heeses. The total vitamin K contents calculated as the sum of quantified K vitamers were in general low (mean content 10-100 ng/g); the highest amount was analyzed in chicken meat (600 ng/g).