Determination of vitamin K in serum using HPLC with post-column reaction and fluorescence detection.

A new, sensitive and selective detection method for vitamin K1 in human serum is reported. After the chromatographic separation, vitamin K is converted to its hydroquinone form in a wet-chemical post-column reduction reaction with tetramethylammonium octahydridotriborate. The reaction proceeds in an open tubular knitted reaction coil at elevated temperature. This system, when combined with a two-step multidimensional liquid chromatographic separation, has proven useful for the quantitative determination of serum concentrations of vitamin K1 in normal, healthy individuals.