Facile synthesis of Fe3O4@CS@ZIF-67 for the magnetic solid phase extraction-high performance liquid chromatographic determination of benzoylurea insecticides in tea infusions

Abstract

In this paper, a novel magnetic metal–organic framework composite with chitosan as linker (Fe3O4@CS@ZIF-67) was synthesized by a facile method at normal pressure and normal temperature. After characterization, Fe3O4@CS@ZIF-67 was used as adsorbent for the magnetic solid phase extraction of benzoylurea insecticides (BUs) in tea infusions prior to high performance liquid chromatographic analysis. The effects of the amount of adsorbent, ionic strength, pH, adsorption time, type of eluent and elution time were investigated. The adsorption could be completed in 1.5 min with only 15 mg adsorbent for the extraction of 10 mL sample solution. Good linearity was obtained for the analysis of BUs with R2 between 0.9988 and 0.9999. The limits of detection were in the range of 0.72–1.48 μg·L−1. Relative standard deviations (RSDs) for intra-day precision and inter-day precision were in the range of 2.62–4.32 % and 3.60–6.29 %, respectively. RSDs for batch-to-batch precision of Fe3O4@CS@ZIF-67 were between 0.41 % and 7.52 %. The spiked recoveries ranged from 75.7 % to 112.5 %. The proposed method has been successfully applied to the determination of BUs in tea infusion samples.