采用气相色谱-质谱（GC-MS）分析技术，选择离子检测法（SIM），建立了减肥食品中芬氟拉明和西布曲明的测定方法。样品经乙醇超声提取，用HP-5 MS石英毛细管柱分离，选择m/z 72、114和159用于SIM检测，并根据提取离子色谱图的峰面积比进行目标物确证，实现了色谱保留时间、质谱特征离子同时定性，消除了减肥食品中复杂基体的干扰，避免了假阳性结果的出现。西布曲明和芬氟拉明在0.1 mg/L~50 mg/L浓度范围内与峰面积之间线性关系良好，在低、中、高3个添加水平范围内的平均回收率为93.8%~97.6%，检测限可以达到1.0mg/kg，可用于减肥食品中非法添加芬氟拉明和西布曲明的检测。

A new method for the determinination of sibutramine and fenfluramine in slimming foods by gas chromatography-mass spectrometry with selected ion monitor (GC-MS/SIM) was established in this paper. The sample was extracted by ethanol, then the chromatographic separation was performed on a HP-5 MS capillary column. The conditions of GC-MS were optimized, and the selected ions were m/z 72, 114 and 159. Qualitative assessment was conducted using both retention time and mass spectrum which the complex matrix disturbance in slimming foods sample could avoided.Quantitative assertion was achieved using base peak m/z 114 and 72, respectively. Good linear was acquired within the range of 0.1 mg/L~50 mg/L, while and recovery rate at three spike levers (low, medium and high) were between 93.8% and 97.6%. The limit of detection was 1.0 mg/kg.The method was proved to be simple and accurate, and could be applied to the determination of sibutramine and fenfluramine in slimming foods flavor with satisfactory results.