Magnetic zinc oxide nanoflower-assisted ionic liquid-based nanofluid dispersive liquid–liquid microextraction for the rapid determination of acaricides in tea infusions

A novel dispersive liquid–liquid microextraction (DLLME) method is proposed for the detection of five acaricides (clofentezine, fenpyroximate, diafenthiuron, pyridaben and spirodiclofen) in tea infusions prior to analysis by high-performance liquid chromatography (HPLC). For this method, a nanofluid prepared by dispersing magnetic zinc oxide nanoflower (FeO4@ZnO) nanoparticles in 1-octyl-2,3-dimethylimidazolium bis(trifluoromethanesulfonimide) was used as an extractant. After extraction, the nanofluid was magnetically collected by the addition of FeO4@ZnO nanoparticles without centrifugation. In DLLME, the joint use of an ionic liquid (IL)-based nanofluid and magnetic retrieval is unprecedented and makes this microextraction process rapid and effective. The main parameters affecting the extraction efficiency were optimized by an orthogonal experiment and a single-factor experiment using tea infusions. Under the optimal conditions, the recoveries of the analytes were between 83.0 and 104.4%, the limits of detection ranged from 0.44 to 1.0 μg L−1, and the intra-day precision and inter-day precision were both lower than 7.5%. The proposed method was successfully applied to the analysis of acaricides in four tea infusions, and the recoveries were between 79.2 and 93.1%, with RSDs of 0.4 to 5.8%. The developed method is promising as an environmentally friendly, convenient, and efficient sample preparation technique.