[Sensitive determination of vitamin K analogues in biological samples by high-performance liquid chromatography using...

To investigate the physiological roles of vitamin K analogues in bone metabolism, especially in osteoporosis, we have developed a sensitive and simple analysis system for vitamin K analogues in the serum and bone. After the separation of vitamin K analogues on a reversed-phase column, the analogues were reduced once in a platinum catalyst reduction column on-line and then monitored quantitatively by electrochemical detector (EICOM ECD-300) operated in the oxidation mode (+0.6 V vs. Ag/AgCl). The detection limits at a signal-to-noise ratio of 3 were 2-10 pg for vitamin K analogues. We also investigated the extraction procedures for the vitamin K analogues from serum and bone. Quantitative recoveries from serum and bone were obtained in the range of 80-101% for vitamin K analogues. We could determine both the circulating vitamin K levels in osteoporotic patients and the vitamin K contents in trabecular and cortical bone of osteoarthritis.