Magnetic solid phase extraction using Fe3O4@β-cyclodextrin-lipid bilayers as adsorbents followed by GC-QTOF-MS for the analysis of nine pesticides

A rapid and efficient magnetic solid phase extraction (MSPE) method, based on Fe3O4@beta-cyclodextrin-lipid bilayer nanocomposites (Fe3O4@beta-CD-LB), was built. The MSPE method coupled with GC-QTOF-MS has been designed for the trace detection of nine organochlorine pesticides (OCPs) in soil samples. The Fe3O4@beta-CD-LB was successfully synthesized and characterized by vibrating sample magnetometry, Fourier transform infrared spectrometry, transmission electron microscopy, field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy. In this experiment, the OCPs in the soil samples were firstly extracted with n-hexane/dichloromethane (v/v 1 : 1) at high pressure and temperature, and then subjected to MSPE for adsorption and purification. Considering the synergy effect between host-guest inclusion complexation and hydrophobic interaction in the adsorption mechanism, the bi-functionalized magnetic nanocomposites exhibited excellent adsorption properties for the OCPs and natural resistance to interference by macromolecules. Under the optimum experimental conditions, the method showed wide linear ranges with low limits of detection (4.5 to 34 pg g(-1)). The results showed that the mean recoveries of the OCPs in the soil samples were 78-107% with 3.0-6.1% intra-day relative standard deviation (RSD) and 3.5-6.9% inter-day RSD. The method has been applied for the determination of the OCPs in actual samples, and sigma OCPs ranged between 0 and 2.3 ng g(-1) in seven soil samples.