Background: A selective and sensitive high-performance liquid chromatographic method with fluorescence detection after postcolumn reduction is described for the routine measurement of vitamin K1 in plasma samples of 100 µL of volume.
Methods: Liquid-liquid extraction was used for the sample preparation with vitamin K2 as an internal standard. For the chromatographic separation, a standard C18 column was applied. The calibration range used was from 2 to 500 ng/mL.
Results: At the low level (5 ng/mL), a coefficient of variation of 14.9% was observed interday in the quality control samples, whereas at the intermediate (50 ng/mL) and high (200 ng/mL) levels such of 6.8% and 8.7% were found.
Conclusions: The method has proven robust and convenient for the analysis of samples from clinical pharmacological studies.