Determination of Vitamin K Analogues by High Performance Liquid Chromatography with Electrochemical Derivatization

A simple, sensitive, and specific method for the determination of phylloquinone (PK) and menaquinone-4 (MK-4) in rat plasma was developed. PK and MK-4 extracted from biological materials were separated by high performance liquid chromatography using a Nucleosil[○!R] C18 column with acetonitrile-isopropyl alcohol as a mobile phase, monitored with a fluorescence detector (ex=330nm, em=430nm) after on-line electrochemical derivatization to fluorescent naphthohydroquinones in an electrochemical reactor. This method was successfully applied to the determination of very small quantities of PK and MK-4 in rat plasma.