Ionic liquid-based totally organic solvent-free emulsification microextraction coupled with high performance liquid chromatography for the determination of three acaricides in fruit juice

Abstract

A novel, totally organic solvent-free emulsification microextraction (TEME) technique using ionic liquids (ILs) is proposed in this study. Seven bis(trifluoromethylsulfonyl)imide ionic liquids were synthesized. After comparing the physicochemical properties of the ionic liquids and their application to microextraction experiments, 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C6MIM][NTf2]), which has moderate surface tension and viscosity, was selected as the extraction solvent. The dispersion of ILs and mass transfer were accelerated by ultrasound irradiation and temperature control processes. Therefore, no dispersive organic solvent was needed. Several variables, such as ionic liquid volume, duration of the ultrasound extraction, dispersion temperature, ionic strength and centrifugation time were investigated and optimized. Under the optimum conditions, the calibration curve was linear in the range of 0.1–600 μg L−1 for chlorfenapyr and fenpyroximate and 0.5–600 μg L−1 for spirodiclofen, with correlation coefficients of 0.9994–0.9999. The enrichment factors were between 261 and 285. The limits of detection (LODs) were 0.02–0.06 μg L−1. Real fruit juice samples (at fortified levels of 10 μg L−1 and 30 μg L−1) were successfully analyzed using the proposed method. The relative recoveries and enrichment factors were in the range of 92–104%.