Dispersive Liquid–Liquid Microextraction of Pesticides Using Ionic Liquids As Extractants

Abstract

It is found that ionic liquids (ILs) based on imidazole can be used as extractants in the dispersive liquid–liquid microextraction of combined pesticide preparations (imidacloprid, biphenthrin, cypermethrin, malathion, phosalone, and diazinon) followed by their determination by HPLC with electrospray ionization tandem mass spectrometry detection with. The effect of the IL (1-hexyl-3-methylimidazolium tetrafluoborate [C6MIM] [BF4], 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [C6MIM] [NTf2], 1‑butyl-3-methylimidazolium hexafluorophosphate, [C4MIM] [PF]6) nature and of the dispersive solvent (acetonitrile, methanol, acetone) volume, extraction time, pH of sample solution, and salting-out agent on the efficiency of analyte extraction is studied. It is found that the maximum recoveries (86–99%) of pesticides were reached using acetonitrile as a dispersive solvent and the [C4MIM] [PF]6 ionic liquid as an extractant. The absence of the effect of pH on the distribution of analytes between the water and organic phases confirms the distributive extraction mechanism. The effect of the ionic liquid on the ionization of pesticides is estimated, and conditions of the back extraction of pesticides to hexane are proposed for its reduction.