采用气相色谱-质谱法测定大米中15种苯氧羧酸类除草剂的残留量。优化的试验条件如下：1提取溶剂为乙腈；2衍生温度为30℃；3衍生时间为20 min；4净化萃取柱为Carbon TPT柱。在气相色谱分离中用PerkinElmer Elite-5MS毛细管柱为固定相，在质谱分析中采用全扫描和多反应监测模式。15种苯氧羧酸类除草剂的线性范围均为0.02~1.00 mg·L^-1，方法的检出限（3S/N）为0.001~0.006 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80.3%~103%，测定值的相对标准偏差（n=5）为4.9%~9.8%。

GC-MS was applied to the determination of residual amounts of 15 phenoxy-hydroxy-acid herbicides in rice. The optimized conditions found were as follows:1 extraction solvent was acetonitrile; 2 derivative temperature was 30℃; 3 derivative time was 20 min; 4 purified extraction column was Carbon TPT column. PerkinElmer Elite-5MS capillary column was used for GC separation. The full-scanning mode and the multiple reaction monitoring mode were adopted in MS determination. Linearity ranges of the 15 phenoxy-hydroxy-acid herbicides were found between 0.02 mg·L^-1 and 1.00 mg·L^-1 with detection limits (3S/N) in the range of 0.001-0.006 mg·kg^-1. On the base of blank sample, test for recovery was made by standard addition method and values of recovery found were in the range of 80.3%-103%, with RSD's (n=5) in the range of 4.9%-9.8%.