Farajzadeh Mir Ali, Mohebbi Ali, Feriduni Behruz
Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran.
Department of Analytical Chemistry, Faculty of Chemistry, University of Tabriz, Tabriz, Iran.
Anal Chim Acta. 2016 May 12;920:1-9. doi: 10.1016/j.aca.2016.03.041. Epub 2016 Mar 29.
In this study, a rapid, simple, and efficient sample preparation method based on continuous dispersive liquid-liquid microextraction has been developed for the extraction and preconcentration of aryloxyphenoxy-propionate herbicides from aqueous samples prior to their analysis by gas chromatography-flame ionization detection. In this method, two parallel glass tubes with different diameters are connected with a teflon stopcock and used as an extraction device. A mixture of disperser and extraction solvents is transferred into one side (narrow tube) of the extraction device and an aqueous phase containing the analytes is filled into the other side (wide tube). Then the stopcock is opened and the mixture of disperser and extraction solvents mixes with the aqueous phase. By this action, the extraction solvent is dispersed continuously as fine droplets into the aqueous sample and the target analytes are extracted into the fine droplets of the extraction solvent. The fine droplets move up through the aqueous phase due to its low density compared to aqueous phase and collect on the surface of the aqueous phase as an organic layer. Finally an aliquot of the organic phase is removed and injected into the separation system for analysis. Several parameters that can affect extraction efficiency including type and volume of extraction and disperser solvents, sample pH, and ionic strength were investigated and optimized. Under the optimum extraction conditions, the extraction recoveries and enrichment factors ranged from 49 to 74% and 1633 to 2466, respectively. Relative standard deviations were in the ranges of 3-6% (n = 6, C = 30 μg L(-1)) for intra-day and 4-7% (n = 4, C = 30 μg L(-1)) for inter-day precisions. The limits of detection were in the range of 0.20-0.86 μg L(-1). Finally the proposed method was successfully applied to determine the target herbicides in fruit juice and vegetable samples.
在本研究中，已开发出一种基于连续分散液液微萃取的快速、简单且高效的样品制备方法，用于在通过气相色谱 - 火焰离子化检测对水样中的芳氧苯氧基丙酸酯类除草剂进行分析之前，对其进行萃取和预富集。在该方法中，两根不同直径的平行玻璃管通过聚四氟乙烯旋塞连接，并用作萃取装置。将分散剂和萃取溶剂的混合物转移到萃取装置的一侧（细管），将含有分析物的水相填充到另一侧（粗管）。然后打开旋塞，分散剂和萃取溶剂的混合物与水相混合。通过这一操作，萃取溶剂作为细小液滴连续分散到水样中，目标分析物被萃取到萃取溶剂的细小液滴中。由于其密度低于水相，细小液滴向上穿过水相，并作为有机层收集在水相表面。最后，取出一份有机相注入分离系统进行分析。研究并优化了几个会影响萃取效率的参数，包括萃取剂和分散剂溶剂的类型和体积、样品pH值和离子强度。在最佳萃取条件下，萃取回收率和富集因子分别为49%至74%和1633至2466。日内精密度的相对标准偏差在3 - 6%（n = 6，C = 30 μg L⁻¹）范围内，日间精密度的相对标准偏差在4 - 7%（n = 4，C = 30 μg L⁻¹）范围内。检测限在0.20 - 至0.86 μg L⁻¹范围内。最后，所提出的方法成功应用于测定果汁和蔬菜样品中的目标除草剂。
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