van Haard P M, Engel R, Pietersma-de Bruyn A L
Clin Chim Acta. 1986 Jun 30;157(3):221-30. doi: 10.1016/0009-8981(86)90297-4.
A sensitive high-performance liquid chromatography method for vitamin K1 using normal-phase fractionation was updated in order to cope with the limited volume of blood samples obtained from newborns. The method combines sample clean-up, normal-phase fractionation with reversed-phase chromatography using post-column electrochemical reduction and fluorescence detection. It was possible to measure vitamin K1 concentration in at least 0.2 ml of (potentially lipemic) serum even at a level of 0.3 nmol/l. The normal-phase method was compared to the updated method. The updated method shows about a twenty-fold lower limit of detectability than the previously described method.
