Development of isotope dilution-liquid chromatography tandem mass spectrometry for the accurate determination of vitamin K1 in spinach and kimchi cabbage

Abstract

In the human body, vitamin K1 is important for bone and cardiovascular health and blood coagulation. To assess the correlation between vitamin K1 intake and health outcomes, the accurate determination of the amounts of vitamin K1 in green leafy vegetables, which are its major source in the diet, is needed. In this study, an accurate method for quantifying naturally occurring trans- and cis-vitamin K1 in spinach and kimchi cabbage was developed on the basis of isotope dilution-liquid chromatography/tandem mass spectrometry (ID-LC/MS/MS). A C30 column was employed for proper separation of trans- and cis-vitamin K1 isomers, and vitamin K1-d7 was used as an internal standard. The developed method was validated by measuring gravimetrically fortified samples, and its performance parameters were evaluated. The measured results agreed with the gravimetric results with a difference of less than 3%. The repeatability and reproducibility of the vitamin K1 analysis were less than 2% relative standard deviation, indicating that the method had a higher-order metrological quality as a reference method.