Determination of vitamin [K.sub.1] in blood serum by high-performance liquid chromatography

A method is proposed for the determination of vitamin [K.sub.1] concentration in blood serum using HPLC on a Gemini C18 (250 mm x 4.6 mm ID, 5 [micro]m) column and elution with a methanol--acetonitrile--dichloromethane (45 : 50 : 5, v/v) mobile phase at a flow rate of 1 mL/min and detection at 248 nm. The limit of detection for the vitamin is 0.5 ng/mL and relative error is 19%. The volume of sample in the column is 100 [micro]L. The method has been applied to the evaluation of vitamin [K.sub.1] deficit in a human body in medical practice.