HPLC–APCI–MS for the determination of vitamin K1 in human plasma: Method and clinical application

A sensitive HPLC–APCI–MS method for the determination of vitamin K1 (VK-1) in human plasma was established. Target ions at [M+H]+m/z 451.5 for VK-1 and [M+H]+m/z 331.4 for the I.S. (teprenone). Calibration curve was linear over the range of 0.3–1000 ng/ml. The lower limit of quantification was 0.3 ng/ml. The intra- and inter-batch variability values were less than 8% and 15%, respectively. The Cmax was 210.1 ± 86.7 ng/ml while the elimination half-life (t1/2) was 8.8 ± 1.7 h and time to the Cmax was 5.5 ± 0.8 h after administration of soft capsule containing 10 mg VK-1.