Abstract A method for the quantitative determination of vitamin K 1 (20)(VK), an essential cofactor in the carboxylation of clotting factors, is presented. The assay is based on gas chromatography/electron impact mass/spectrometry. The preparation of deuterium-labelled vitamin K 1 (20) for use as an internal standard is described. The method involves extraction of VK from human plasma and its derivatization to the heptafluorobutyryl ester after ...
