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建立了高效液相色谱-四极杆／静电场轨道阱高分辨质谱法测定奶粉中低聚果糖的方法。奶粉样品用水溶解，加乙酸锌沉淀蛋白，经离心、0.22μm 粒径的微孔膜过滤后，采用 Carbohydrate 色谱柱（100 mm ×2.1 mm，2.6μm）进行分离，以乙腈与0.1％乙酸水溶液为流动相进行梯度洗脱。质谱采用正离子 Target-MS／MS 模式，在分离窗口为 m／z 4.0和碰撞能为30 eV的条件下，提取响应值较高且在待测样品中无干扰的目标子离子的精确质量数，此方法能够很好地排除样品中的基质干扰。在所建立的色谱-质谱条件下，蔗果三糖（GF2）、蔗果四糖（GF3）和蔗果五糖（GF4）能够得到较好的分离，高分辨质谱提取的质量准确度小于5×10－6（5 ppm），整个分析时间只需10 min。该方法对 GF2和 GF3的检出限可达100μg／kg，对 GF4的检出限可达55μg／kg。待测物质采用外标法定量，线性关系良好，相关系数均大于0.998。通过加标验证，在5、10和20 mg／kg 3个加标水平下，奶粉中 GF2、GF3和 GF4的平均回收率在75.8％~107.3％范围内，相对标准偏差（ RSD）在1.6％~8.3％范围内。该方法样品前处理过程简单，只需沉淀蛋白质，通过二级子离子的选择即可排除基质干扰，分析时间短，测定结果准确、可靠，适用于任何奶粉的高通量测定。

A method of high performance liquid chromatography-quadrupole/electrostatic field Orbitrap high resolution mass spectrometry( HPLC-Q/Orbitrap MS ) was developed to deter-mine fructo-oligosaccharides in milk powder. The milk powder samples were dissolved in deion-ized water. Subsequently,an aqueous solution of zinc acetate was used to precipitate protein. After centrifugation, the final aqueous solution was filtered by a polytetrafluoroethylene ( PTFE)membrane with pore size of 0. 22 μm. The analytes were separated on a Carbohydrate column(100 mm×2. 1 mm,2. 6 μm)through gradient elution with the combination of acetoni-trile and 0. 1% formic acid aqueous solution. The target-MS/MS templates were performed at isolation window of m/z 4. 0 and collision energy of 30 eV in positive mode to extract the accu-rate product ion mass of analytes. Under the optimal condition,1-kestose( GF2),nystose (GF3)and 1-F-β-fructofuranosyl nystose(GF4)were well separated and the accuracy of extracted mass routinely detected was below 5×10-6(5 ppm). The whole analysis time is only ten minutes. The detection limits for GF2 and GF3 were 100 μg/kg,and the detection limit for GF4 was 55 μg/kg. Good linearities were obtained in their respective linear ranges with correla-tion coefficients higher than 0. 998. The average recoveries at three spiked levels(5,10 and 20 mg/kg)were in the range of 75. 8%-107. 3% and the relative standard deviations( RSDs)were in the range of 1. 6%-8. 3%. The proposed method is simple,sensitive,fast and only in need of precipitation of proteins. The interference of matrix can be eliminated through the selection of product ion. The results were convenient and reliable and thus can be used in the large batch determination of any milk powder.