Facile preparation of magnetic covalent organic framework-metal organic framework composite materials as effective adsorbents for the extraction and determination of sedatives by high-performance liquid chromatography/tandem mass spectrometry in meat samples.

Rationale: Sedatives, which are prone to cause residues in animals, have been abused in modern animal husbandry. Long-term consumption of contaminated meat products would be unfavorable to the human nervous system. Taking into account public health and food safety, it was essential to develop an effective method for the enrichment and detection of sedatives in meat.

Methods: Fe O @TbBd@ZIF-8 composites were synthesized by using Fe O nanoparticles as a magnetic core and 1,3,5-triformylbenzene (Tb) and benzidine (Bd) as two building blocks to form Fe O @TbBd. Furthermore, the zeolitic imidazolate framework-8 (ZIF-8) was modified on the surface of the Fe O @TbBd. In addition, Fe O @TbBd@ZIF-8 was used as a magnetic solid-phase extraction (MSPE) adsorbent of typical animal sedatives in pork samples. Mass spectrometry analysis was conducted by electrospray ionization triple-quadrupole mass spectrometry in positive-ion multiple reaction monitoring mode.

Results: By combining the optimized MSPE approach with high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS), an accurate and sensitive method for the determination of sedatives was developed. The method exhibited good linearity in the range of 0.03-70 μg/kg with the correlation coefficient (R ) ranging from 0.9982 to 0.9999, high sensitivity with limits of detection (LODs) ranging from 0.04 to 0.2 μg/kg, and high precision with relative standard deviation (RSD) less than 5.5%. The adsorption behaviors of Fe O @TbBd@ZIF-8 towards sedatives were more suitably described by a pseudo-second-order kinetic and Freundlich isotherm model.

Conclusions: The proposed MSPE-HPLC/MS/MS method was successfully applied to the determination of sedatives in real samples and showed excellent applicability. Several sedatives were detected in the selected meat samples. The developed method was shown to be facile, sensitive and accurate for sedative detection and also showed great prospects for determination of sedatives from other complex samples.