A Novel Ionic Liquid of [BeMIM] [Tf2N] for Extracting Pesticides Residues in Tea Sample by Dispersive Liquid–Liquid Microextraction

Abstract

In this work, a novel 1-benzyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([BeMIM][Tf2N]) ionic liquid (IL) was used for extracting three organophosphorus pesticides (OPPs) (ethoprophos, fenitrothion, and phoxim) from tea samples by dispersive liquid–liquid microextraction (DLLME). The OPPs were detected by high-performance liquid chromatography (HPLC) with UV detector. Four [Tf2N]-based ILs were compared during the extraction process, and [BeMIM][Tf2N] showed the best performance. Acetonitrile was used as an extracting solvent in the extracting process and as a dispersant solvent in the DLLME process. Several parameters affecting the performance of the method including the selection of extraction solvent type, dispersant type, pH, extraction time, extraction temperature, salt addition, and centrifugation time were optimized. Under the optimal conditions, the enrichment factors of the analytes were in the range of 242.8–266.0, and the limit of detection was 0.1 μg/kg. The optimized method was also used for testing tea samples from different brands. The recoveries of the analytes were between 78.8 and 102.2%, with the RSDs were in the range of 0.9–4.5. The developed method is low-cost, time-saving, and reagent-saving; it is a promising and efficient sample technique for solid-sample preparation.