Liquid chromatographic dual electrode detection system for vitamin K compounds.

An electrochemical detection approach for vitamin K1 (phylloquinone) in combination with high-performance liquid chromatography is described utilizing two sequential generator/detector electrodes. Vitamin K is first electrolyzed, and then the reaction product is detected electrochemically at a second electrode. The minimum level of K1 detected in these experiments was about 100 pg. 2-Chloro-vitamin K1, 2',3'-dihydrovitamin K1, and vitamin K2 (menaquinones) were all electroactive. Vitamin K epoxide was not electroactive. Application of the technique for detection of vitamin K1 in rat liver is illustrated. The electrochemical detector was found to be superior to the ultraviolet detector in terms of sensitivity and selectivity for vitamin K1.