提出了分散固相萃取-气相色谱法同时测定大米中37种农药残留量的方法.采用C18、乙二胺-N-丙基硅烷(PSA)和无水硫酸镁固相材料分散净化技术,以丙酮-正己烷(25+75)溶液为萃取溶剂,用脉冲火焰光度检测器和电子捕获检测器同时测定37种农药.13种有机氯农药的线性范围为0.02~0.2 mg·L-1,16种有机磷农药和8种拟除虫菊酯农药的线性范围为0.1~1.0 mg·L-1,方法的检出限(3S/N)均小于0.02 mg·kg-1.以大米样品为基体,加入三种不同浓度的农药标准溶液作回收试验,测定回收率在71.8%~111.8%之间,相对标准偏差(n=3)在1.1%~14.0%之间.

Thirty-seven pesticides in rice were determined simultaneously by GC with PFPD and ECD after separation by dispersive-solid phase extraction (DSPE).Sample of rice was extracted homogeneously with mixture of acetone-hexane(25+75) as dispersion agent.The extract obtained was purified by DSPE through shaking with mixture of C18,ethylene diamine-N-propylsilane (PSA) and anhydrous magnesium sulfate in the sample flask.The supernatant was used for GC analysis with PFPD and ECD.Linearity ranges of 13 organochlorine,16 organophosphorous and 8 pyrethroid pesticides were kept in the ranges of 0.02-0.2 mg·L-1,0.1-1.0 mg·L-1 and 0.1-1.0 mg·L-1 respectively.Detection limits (3S/N) found were less than 0.02 mg·kg-1.Tests for recovery and precision were made by addition of standard solutions of the 37 pesticides at 3 different concentration levels to rice sample which was then analyzed by the proposed method.Values of recovery obtained were in the range of 71.8%-111.8% and values of RSD′s (n=3) were in the range of 1.1%-14.0%.