Determination of phylloquinone and menaquinone in human milk using high performance liquid chromatography.

A high performance liquid chromatographic method for measuring vitamin K in human milk and cow milk is described. The K vitamins were extracted with n-pentane from enzymatic hydrolysate of milk, purified by semipreparative HPLC, and then analyzed by reversed-phase HPLC equipped with a dual electrochemical detector. The amount of phylloquinone and menaquinone-4 in human milk was 2.1 +/- .9 and 1.3 +/- 1 microgram/L, respectively (n = 23). A small amount of menaquinone-6 was detected in both human and cow milk.