高效液相色谱法测定食品中维生素K1和维生素K2的含量

建立高效液相色谱-荧光检测法（HPLC-FLD）测定食品中维生素K₁和维生素K₂含量的分析方法。方法：配方奶粉、酸奶、纳豆冻干粉和鸡胗冻干粉经酶解、异丙醇分散、正己烷萃取、旋转蒸发复溶后，使用Thermo Acclaim^TM 120 C₁₈色谱柱（150 mm×4.6 mm，5 μm）分离，锌粉还原柱（50 mm×4.6 mm）衍生，以900 mL甲醇：100 mL四氢呋喃（含冰醋酸0.3 mL，氯化锌1.5 g，无水乙酸钠0.5 g）为流动相，激发波长为243 nm，发射波长为430 nm，分离维生素K₁（Vitamin K₁，VK₁）、四烯甲萘醌（menaquinone-4，MK-4）、七烯甲萘醌（menaquinone-7，MK-7）和九烯甲萘醌（menaquinone-9，MK-9）。结果：VK₁、MK-4、MK-7和MK-9在20~1000 μg/L范围内与峰面积有良好线性关系。配方奶粉、酸奶、纳豆冻干粉和鸡胗冻干粉中VK₁、MK-4、MK-7、MK-9含量的相对标准偏差（RSD）均小于5%，表明精密度好。配方奶粉、酸奶和纳豆冻干粉不同水平加标回收率分别为85.0%~107.8%、85.8%~109.6%、85.1%~102.7%，回收率的RSD均小于5%，表明回收率高，相对标准偏差小。结论：实验建立的方法重复性好、准确度高，可以精准定量食品中维生素K₁和维生素K₂的含量。

Determination of Vitamin K1 and Vitamin K2 in Foods by HPLC-FLD

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 Acclaim^TM 120 C 18 column(150 mm×4.6 mm,5μm)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 VK 1、MK-4、MK-7、MK-9 were 20~1000μg/L.The relative standard deviation(RSD)of VK 1,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 VK 1,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.