[Vitamin K]

In this paper, highly sensitive methods for measuring of vitamin K in serum, feces and milk are described. Vitamin K1 and the menaquinone family from the serum, feces and milk were separated by high performance liquid chromatography. The separated K1 and menaquinone families were detected by a fluorescence spectrophotometer after their reduction with sodium borohydride or platinum catalyst column. In these methods, minimum detectable quantities of K1, menaquinone-4 and menaquinone-7 were 10, 10 and 50 pg, respectively. More than 95% of supplemented vitamin K1, menaquinone-4 and menaquinone-7 were recovered in the serum and feces. Furthermore, the method of Hirauchi et al. for measurement of vitamin K1 2,3-epoxide in human plasma is introduced.