Application Of The Ionic Liquid-dispersive Liquid Liquid Microextraction Technique In Solid Matrix Of Wheat And The Investigation Of The Structure-activity Relationship Of Ionic Liquid

Ionic liquid (IL) as extraction solvent in dispersive liquid-liquid microextraction(DLLME) has been widely used to extract, enrich and determination of many substances.Various functionalized ionic liquids show different extraction abilities. In this paper,IL-DLLME was used to detect pesticides in the solid matrix of wheat, and the experimentalparameters influencing the extraction efficiency were optimized. Furthermore, chemometricmethod was applied to study the relationship between extraction efficiency of IL to organiccompounds and their structure.A two-step extraction technique, combining magnetic stirring extraction (MSE) and ionicliquid based-dispersive liquid-liquid microextraction (IL-DLLME), was developed forenrichment and determination of three organochlorine pesticides (o, p’-DDE, o, p’-DDT and p,p’-DDT) in wheat solid matrix. A feature of the proposed procedure is that the extractionsolvent in MSE and the dispersive solvent in DLLME is the same solvent (acetonitrile).Functional ionic liquid,1-benzyl-3-methylimidazolium bis [(trifluoromethyl)sulfonyl]imide([BeMIM][Tf2N]), was used as extraction solvent in DLLME. Experimental parametersaffecting MSE and DLLME procedure were investigated in detail, including type and volumeof extraction and dispersive solvent, time and temperature of magnetic stirring andcentrifugation time. The enrichment factor and extraction recovery were in the range of178.4-188.7and59.2%-63.1%, respectively. The linear range of this method was0.1-100.0μg/g with RSD of2.0-7.4%(n=5). The detection limit was1.0ng/g.Ionic liquid based dispersive liquid-liquid microextraction assisted by ultrasonicextraction (USE) was applied to extract three organophosphorus pesticides (fenitrothion,fenthion and phoxim) in wheat samples by using1-octyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ionic liquid ([OMIM][Tf2N]) as extractant solvent, and theextraction solvent in ultrasonic assisted extraction and the dispersive solvent in DLLME is thesame solvent (methanol). Experimental parameters affecting ultrasonic assisted extraction andDLLME procedure were investigated in detail, including type and volume of extraction anddispersive solvent, time of ultrasonic assisted extraction and temperature of DLLME. Theenrichment factor of organophosphorus pesticides in wheat samples was in the range of203.8-332.4, and the extraction recovery was in the range of44.4-64.3%. The linearity range of this method was0.01-100μg/g with RSD of0.6-6.3%(n=5). The detection limit was0.1ng/g.At last, the relationship between extraction efficiency of IL to organic compounds andtheir structure was investigated. The quantitative structure-activity relationship (QSAR)modeling was made by applying electrotopological state indices (E-state indices) of16oganiccompounds and their enrichment factors obtained by1-octyl-3-methylimidazoliumhexafluorophosphate-DLLME. The enrichment factors of8oganic compounds weresucessfully predicted. The model analysis showed that there is a good correlation between theextraction results of analytes and the electrotopological state indices, correlation coefficent ofthe model is0.992.