分散液液微萃取-保留时间锁定-气相色谱质谱联用测定地表水中34种农药

Determination of 34 pesticide residues in surface water by DLLME- RTL- GC- MS

目的建立了一种地表水中34种农药残留的分散液液微萃取-保留时间锁定-气相色谱质谱联用快速筛查及定量方法。方法通过分散液液微萃取(DLLME)提取水中的农药残留,对DLLME萃取相关的影响因素如萃取溶剂种类与体积,分散溶剂种类及体积,盐的浓度等进行了优化。最终优化的萃取条件如下:35μl四氯化碳与1 ml丙酮混匀后作为萃取溶剂,通过注射器迅速注射入5 ml水样中,经过离心获得25μl沉积相,吸取其中20μl与1μl环氧七氯内标溶液混合后用保留时间锁定气相色谱-质谱法(RTL-GC-MS)测定。结果通过三个水平六平行的加标回收实验,方法的回收率范围为50%～148%,相对标准偏差(RSD)为4.7%～50%,富集因子为101倍～297倍,方法的检出限(LOD)范围为0.002μg/L～0.065μg/L,定量限(LOQ)为0.007μg/L～0.217μg/L。结论本方法是一种快速,准确,高灵敏度的微萃取方法,能够应用于地表水中多农药监测。

Objective A rapid screening and quantification method based on DLLME RTL GC MS was developed to deter mine 34 pesticides in surface water. Methods The pesticide residues were extracted from water using DLLME. Several param eters of the extraction procedure such as type and volume of extraction solvent, type and volume of disperser solvent and salt ad dition were optimized. A mixture of 35 μl carbon tetrachloride （extraction solvent） and 1 ml acetone （disperser solvent） was used as extraction reagent, injected into 5 ml water sample. After centrifugation, 20 μl of the 25 μl sedimented phase was draw up by a syringe and 1 μl inner standard （ I. S. ） was injected to form the final mixed solution for determination by RTL GC MS. Results The average recoveries for pesticides at three different levels ranged from 50% to 148%. The relative standard deviation （RSD） at three levels ranged from 4.7% to 50%. The enrichment factors from 101 to 297 folds were obtained for all compounds. The LODs of 34 pesticides ranged from 0. 002μg/L to 0. 065 μg/L, and the LOQs ranged from 0. 007 μg/L to 0.217 μg/L. Conclusion The method is rapid, accurate and sensitive, it can be applied in screening and quantification of multi pesticides in surface water.