向已加入100 mg氯化钠的5.0 mL水样中加入由20.0 μL四氯乙烯、1.0 mL丙酮混合而成的分散微萃取溶液，采用气相色谱-质谱法测定萃取相中环氧七氯的含量。在气相色谱分离中采用DB-5ms石英毛细管色谱柱，在质谱分析中采用选择离子监测模式。环氧七氯的质量浓度在0.5~200 μg·L^-1内与其对应的峰面积呈线性关系，检出限（3S/N）为0.1 μg·L^-1。以空白样品为基体进行加标回收试验，所得回收率为81.6%~97.4%，测定值的相对标准偏差（n=5）为4.6%~7.2%。

A dispersive microextraction solution composed of 20.0 μL of tetrachloroethylene and 1.0 mL of acetone was added into the water sample (5.0 mL) which was added NaCl (100 mg). GC-MS was applied to the determination of heptachlor epoxide in the extract phase. The DB-5ms quartz capillary chromatographic column was used for GC separation and the selected ion monitoring mode was adopted in MS determination. Linear relationship between values of peak area and mass concentration of heptachlor epoxide was kept in the range of 0.5-200 μg·L^-1, with detection limit (3S/N) of 0.1 μg·L^-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 81.6%-97.4%, with RSDs (n=5) of determined values in the range of 4.6%-7.2%.