Laboratory of Analytical Chemistry and Electrochemistry, Faculty of Engineering, University of Zulia, P.O. Box 4011-A-526, Maracaibo, Venezuela,
Environ Monit Assess. 2013 Dec;185(12):10225-33. doi: 10.1007/s10661-013-3327-8. Epub 2013 Jul 27.
An analytical method for the determination of diflufenican, mepanipyrim, pretilachlor, and fipronil in water samples was developed using single drop microextraction in the direct immersion mode and gas chromatography-mass spectrometry. A factorial fractionated design of type 2(6-1) at two levels was performed, to study the influence of experimental variables such as ionic strength, pH, agitation speed, extraction time, drop volume, and sample volume. To establish the optimal conditions for the variables that were significant, a Doehlert design was performed. The optimum conditions of extraction were 1 μL of heptane immersed in 4.0 mL of sample with continuous agitation at 500 rpm for 30 min at room temperature. The developed method proved to have good linearity for the range studied. The detection limits were 0.07 μg L(-1) for diflufenican, 0.03 μg L(-1) for mepanipyrim, 0.08 μg L(-1) for pretilachlor, and 1.39 μg L(-1) for fipronil. The method was validated on river water samples, showing the absence of matrix effect and recoveries ranged from 90.1 to 107.8 %. The results show that the method developed is accurate, sensitive, rapid, simple, and low cost, so it is recommended for application in the analysis of these different classes of pesticides in water samples.
采用直接浸入式单滴微萃取技术与气相色谱-质谱联用，建立了一种测定水样中氟吡菌胺、双氟磺草胺、丙草胺和氟虫腈的分析方法。采用二水平 2(6-1)析因设计，研究了离子强度、pH 值、搅拌速度、萃取时间、液滴体积和样品体积等实验变量的影响。为了确定有显著影响的变量的最佳条件，进行了 Doehlert 设计。萃取的最佳条件为：室温下，在 4.0 mL 样品中浸入 1 μL 正庚烷，以 500 rpm 的速度连续搅拌 30 min。所建立的方法对研究范围内的浓度具有良好的线性关系。检测限分别为氟吡菌胺 0.07 μg L(-1)、双氟磺草胺 0.03 μg L(-1)、丙草胺 0.08 μg L(-1)和氟虫腈 1.39 μg L(-1)。该方法在河水样品中的验证表明，不存在基质效应，回收率在 90.1%至 107.8%之间。结果表明，所建立的方法准确、灵敏、快速、简单、成本低，因此推荐用于水样中不同类别的农药分析。
