液相色谱-大气压化学电离串联质谱法测定婴幼儿配方奶粉中的维生素D

建立了婴幼儿配方奶粉中维生素D的液相色谱-大气压化学电离串联质谱(LC-APCI-MS/MS)分析方法。样品经正己烷和甲基叔丁基醚混合溶液提取,ProElut VDC固相萃取柱净化,Kinetex C_(18)色谱柱分离,采用大气压化学电离(APCI)源、正离子扫描和多反应监测(MRM)模式对维生素D_2和维生素D_3进行检测,内标法定量。结果表明维生素D_2和维生素D_3在5~5 000μg/L范围内均具有良好的线性关系,检出限为2μg/kg,定量限为5μg/kg。在5、10和100μg/kg添加水平下,维生素D_2和维生素D_3的回收率为85.2%~105.3%,相对标准偏差为4.7%~8.1%。该方法简便准确,灵敏度高,适用于婴幼儿奶粉中维生素D的测定。

Determination of vitamin D in infant formula using liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry

A method using liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry (LC-APCI-MS/MS) was developed for the determination of vitamin D in infant formula. The milk powder sample was extracted with hexane and tert-butyl methyl ether followed by clean-up with ProElut VDC cartridge. The LC separation was performed on Kinetex C₁₈ column (100 mm×4.6 mm, 2.6 μm) by a gradient elution using water and acetonitrile as the mobile phases with a flow rate of 1.0 mL/min. Identification of vitamin D₂ and vitamin D₃ was achieved by APCI-MS/MS using multiple reaction monitoring (MRM). The quantification analysis was performed by internal standard method. The calibration curves showed a good linearity in the range of 5-5000 μg/L. The limits of detection (LODs) for vitamin D₂ and vitamin D₃ in the formula were 2 μg/kg. The limits of quantification (LOQs) for vitamin D₂ and vitamin D₃ in the formula were 5 μg/kg. The average recoveries of vitamin D from milk powder spiked at 5, 10 and 100 μg/kg levels were between 85.2% and 105.3%, and the relative standard deviations were between 4.7% and 8.1%. The simple, accurate and sensitive method is suitable for the determination of vitamin D in infant formula.