Determination of Vitamin K 1 and Vitamin K 2 in Foods by HPLC-FLD

Abstract

An analytical method was developed for determining vitamin K1 and vitamin K2 in foods by high performance liquid chromatography with Fluorescence Detector(HPLC-FLD). Milk powder,yoghurt,natto freeze-dried powder and chicken gizzard freeze-dried powder were hydrolyzed by enzyme,dispersed by isopropanol,extracted by n-hexane,evaporated by rotation and redissolved. The separation of vitamin K1(VK1),menaquinone-4(MK-4),menaquinone-7(MK-7)and menaquinone-9(MK-9)were achieved on Thermo AcclaimTM120 C18 column(150 mm×4.6 mm,5 μm)and derivatived by zinc powder reduction column(50 mm×4.6 mm)using 900 mL methanol:100 mL tetrahydrofuran(containing 0.3 mL glacial acetic acid,1.5 g zinc chloride,0.5 g anhydrous sodium acetate)as the mobile phase at excitation wavelength was 243 nm,emission wavelength was 430 nm. The results showed that the linear range of VK1、MK-4、MK-7、MK-9 were 20~1000 μg/L. The relative standard deviation(RSD)of VK1,MK-4,MK-7,MK-9 in dried milk,yoghurt,natto freeze-dried and chicken gizzard were less than 5%,indicating high precision. The recovery rate of VK1,MK-4,MK-7 and MK-9 in dried milk,yoghurt,natto freeze-dried were 85.0%~107.8%,85.8%~109.6%,85.1%~102.7% and RSD were less than 5%,indicating high recovery rate and small relative standard deviation. Therefore,this developed method is high reproducibility and accuracy. It can be applied to accurate determine of vitamin K1 and vitamin K2 in foods.