采用气相色谱-质谱法测定食品接触材料聚对苯二甲酸乙二醇酯塑料中间苯二甲基异氰酸酯的残留量。样品1.000 g经5 mL乙酸乙酯超声提取25 min，上清液用乙酸乙酯定容至10 mL后，经0.45 μm有机系微孔滤膜过滤。在气相色谱分离中采用HP-5MS石英毛细管色谱柱，在质谱分析中采用全扫描和选择离子监测模式。间苯二甲基异氰酸酯的质量浓度在0.05~5.0 mg·L^-1内与其对应的峰面积呈线性关系，测定下限（10S/N）为0.05 mg·kg^-1。以空白样品为基体进行加标回收试验，所得回收率为79.2%~93.4%，测定值的相对标准偏差（n=7）为0.83%~4.5%。

GC-MS was applied to the determination of residual amount of m-xylylene diisocyanate in food contact materials of PET plastic. The sample (1.000 g) was extracted ultrasonically with 5 mL of ethyl acetate for 25 min, and then the supernatant was diluted to 10 mL with ethyl acetate. The above sample solution was taken and filtered on 0.45 μm organic microporous filter membrane. The HP-5MS quartz capillary chromatographic column was used for GC separation and the full scanning mode and the selected ion monitoring mode were adopted in MS determination. Linear relationship between values of peak area and mass concentration of m-xylylene diisocyanate was kept in the range of 0.05-5.0 mg·L^-1, with lower limit of determination (10S/N) of 0.05 mg·kg^-1. On the base of blank sample, test for recovery was made by standard addition method; values of recovery found were in the range of 79.2%-93.4%, with RSDs (n=7) in the range of 0.83%-4.5%.