原位衍生分析土壤中多种酸性有机农药残留

为克服土壤中酸性有机农药测定的预处理过程复杂、回收率低和二次污染严重等不足，建立了土壤中酸性有机农药原位衍生分析方法。将土壤样品、Na₄-EDTA和水混合均匀，待水分挥发后将样品转移至衍生瓶中，以五氟苄基溴为衍生试剂进行原位超声衍生；萃取液经净化后，采用负化学电离源(NCI)选择离子监测模式测定；同时讨论了络合萃取条件、衍生条件、净化条件、负化学源质谱条件及土壤TOC对样品分析的影响。结果表明：该方法在5~500 μg/L线性范围内，各组分响应峰面积与其相应浓度的线性相关系数r²大于0.998 0；空白基质中不同浓度的加标回收率在80%~110%之间（n=7），相对标准偏差在8.2%~13%之间（n=7）。应用该方法对不同地域的实际土壤样品进行分析检测，检出了多数酸性有机农药。

In Situ Derivatization Analysis of Acidic Organic Pesticide Residues in Soil

In order to overcome the defect of the pretreatment process of acidic organic pesticides for soil samples, such as complicated, low recovery and large secondary pollution and so on, in situ derivative method for acidic organic pesticide residues in soil was established. The soil sample, Na₄-EDTA and pure water were mixed sufficiently, and then transfered the sample into a derivative bottle after the water evaporated, used 2,3,4,5,6-pentafluoro-benzyl bromide as derivative reagents for in situ ultrasonic derivatization. The proposed compounds were separated and analyzed by gas chromatography-negative chemical ionization mass spectrometry(NCI) after the extract was purified. A series of factors affected sample analysis, such as complexation extraction condition, derivatization condition, purification condition, negative chemical ionization mass spectrometry condition and soil TOC, were all well studied and carefully optimized. The results show that the linearity range is 5-500 μg/L with the correlation coefficients greater than 0.998 0. The spiked recoveries of different concentrations range from 80% to 110% with the relative standard deviations of 8.2%-13% (n=7). Real sample is analyzed by this method, and some of proposed acidic organic pesticides are detected in some soils.