提出了用气相色谱法测定毛豆中3种残留杀虫剂(氟虫腈、溴虫腈及茚虫威)的灵敏方法.用正己烷-丙酮(1+1)的混合溶液将样品中3种杀虫剂萃取分离.分取所得萃取液2 mL两份,分别用所提出的两组不同SPE微柱和两种不同的混合溶剂进行纯化和淋洗处理.一种处理所得溶液供测定氟虫腈及溴虫腈之用,另一种处理所得溶液供测定茚虫威之用.在气相色谱分析中采用HP-5毛细管色谱柱(30 m×320 mm,0.25 μm),微池电子捕获检测器和外标法定量.对方法的回收率及精密度作了试验,测得回收率在64.3%~92.8%之间,相对标准偏差(n=5)在5.3%~10.8%之间.此方法对3种杀虫剂的测定下限(10S/N)依次为0.5,0.5及2.5 μg·kg-1.

A sensitive GC method for determination of 3 residual insecticides,i.e.,fipronil,chlorfenapyr and indoxacarb,was reported in this paper.The residual insecticides were extracted from the sample with a mixed solvent of acetone and n-hexane (mixed in the ratio of 1 to 1 by volume).Two mL portions of the extract were taken and purified by SPE and elution.Two different SPE micro columns and 2 different solvent mixtures were used in the purification and elution processes,one for determination of fipronil and chlorfenapyr,and the other for determination of idoxacarb.HP-capillary chromatographic column (30 m×320 mm,0.25 μm) and μECD detector as well as the method of external standard were adopted in the GC analysis.Tests for recovery and for precision were made and values of recovery and RSD′s (n=5) obtained were in the ranges of 64.3%-92.8% and 5.3%-10.8%.Lower limits of determination (10S/N) found were 0.5,0.5 and 2.5 μg·kg-1 respectively.