Chemical synthesis–free and facile preparation of magnetized polyethylene composite and its application as an efficient magnetic sorbent for some pesticides

Abstract

In this study, a magnetized polyethylene composite has been prepared using ball milling procedure and employed as an efficient sorbent in magnetic dispersive solid phase extraction combined with dispersive liquid–liquid microextraction. This method has been utilized for the extraction and preconcentration of some pesticides from fruit juices prior to their quantification by gas chromatography–flame ionization detection. The prepared sorbent consisted of the natural iron oxide (obtained from sand) coated with polyethylene. In the present work, first a few mg of the magnetic composite is added into an aqueous solution containing the analytes and vortexed. After that the analytes are eluted with iso–propanol from the surface of the composite particles separated in the presence of a strong external magnetic field. For further enrichment of the analytes, 1,2–dibromoethane (at µL–level) as an extraction solvent is mixed with the obtained eluent and hastily injected into deionized water. The composite was characterized using techniques including vibrating sample magnetometry, X–ray diffraction, scanning electron microscopy, energy–dispersive X–ray spectroscopy, Brunauer–Emmett–Teller nitrogen sorption, and Fourier transform infrared spectrophotometry. Under optimal conditions, the method provided low limits of detection (0.94–1.9 μg L−1) and quantification (3.2–5.9 μg L−1), high enrichment factors (570–692), good linearity (r2 ≥ 0.994), and satisfactory repeatabilities (relative standard deviations ≤ 8% for intra– and inter–day precisions at a concentration of 15 μg L−1 of each analyte).