Determination of Vitamin K in Plasma by High Performance Liquid Chromatography with Electrochemical Detection

Abstract

Although the methods of high-performance liquid chromatography with electrochemical detection for the determination of vitamin K (K_s) in human plasma had already reported, they have some problems including the effect of dissolved oxygen in mobile phase on background current, losing sensitivity of electrode due to adsorption of reducted compounds on to the surface of the electrode, and single determination for phylloquinone (K_1). For the resolution of these problems, we tried to use a platinum black column for the reduction of K_s instead of electrochemical reduction, and an amperometric electrochemical detector in the oxidation mode. Therefore, we developed a sensitive method for the simultaneous determination of K_1 and menaquinons (MK-4, MK-7) in human plasma. The detection limits in the present method were 0.05 ng/ml of K_1, MK-4 and 0.1 ng/ml of MK-7.