提出了气相色谱-质谱法测定烟草中酰胺类除草剂异丙甲草胺、双苯酰草胺和敌草胺的残留量的方法。样品用乙酸乙酯-环己烷(1+1)混合溶剂提取,所得提取液用凝胶渗透色谱进行净化,用乙酸乙酯-环己烷(1+1)混合溶剂作流动相。采用气相色谱分离后,选择离子监测模式下质谱法进行测定。异丙甲草胺、双苯酰草胺和敌草胺的检出限(3S/N)分别为0.45,0.50,0.30 ng·g-1。加入两个浓度水平的混合标准溶液进行了回收试验,所得回收率在90.0%~102.0%之间,相对标准偏差(n=6)在2.5%~3.2%之间。

A method for determination of residual amounts of 3 acetanilide herbicides, i.e. metolachlor, diphenamide and napropamide, in tobacco by GC-MS was proposed. Samples were extracted with mixed solvent of ethyl acetate and n-hexane (1+1). The extract obtained was purified by gel permeation chromatography using mixed solvent of ethyl acetate and n-hexane (1+1) as mobile phase. The eluates were taken for separation by GC and the contents of 3 acetanilide herbicides were determined by MS under select ion monitoring (SIM) mode. Values of detection limit (3S/N) found were 0.45 ng·g-1 for metolachlor, 0.50 ng·g-1 for diphenamide, and 0.30 ng·g-1 for napropamide. Tests for recovery were made by addition of mixed standard solution at 2 different concentration levels, values of recovery found were in the range of 90.0%-102.0%, with values of RSD′s (n=6) in the range of 2.6%-3.2%.