Determination of Vitamin K1,Menaquinone-4 and Menaquinone-7 in Food
A method for simultaneous determination of vitamin K1,menaquinone-4(MK-4)and menaquinone-7(MK-7)content in food was established,and to evaluate the levels of vitamin K in different foods.After enzymatic hydrolysis and n-hexane extraction,food samples were analyzed by liquid chromatography-tandem mass spectrometry.The chromatographic separation was carried out on an Agilent Poroshell 120 EC-C18 column(50 mm×3.0 mm,2.7 μm),with 0.1％ formic acid acetonitrile and 0.1％ formic acid methanol as mobile phase gradient elution.Mass spectrometry method was carried out with atmospheric pressure chemical ionization source,multiple reaction monitoring mode for positive ion detection.Under the optimum conditions,vitamin K1,MK-4 and MK-7 were determined within 4 min.All analytes achieved good linearity in the range of 0.5-500.0 ng/mL,with correlation coefficient higher than 0.9932.The recoveries rates of standard addition were between 87.5％ and 110.7％,with the relative standard deviations less than 7.09％.The method was applied to determine the content of vitamin K in 27 kinds of food,the content of vitamin K1 was higher in vegetable foods,MK-4 was the main vitamin K in meat and eggs,and MK-7 was higher in fermented soybean products.The method was simple,reproducible and accurate,and was suitable for the determination of vitamin K1,MK-4 and MK-7 in food.
vitamin K1menaquinone-4menaquinone-7foodliquid chromatography-tandem mass spectrometry
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