Synthesis of a boronic acid-functionalized magnetic covalent organic framework for selective extraction and determination of macrolide antibiotics in water and milk samples.

A novel boronic acid-functionalized magnetic covalent organic framework (Fe3O4@Tp-PaV@MPBA) was prepared as magnetic solid phase extraction (MSPE) sorbents for selective extraction of seven macrolides in water and milk samples. The combination of COFs and boronic acid ligands endowed the material with large specific surface area and specific recognition sites. Adsorption kinetic and isotherm study showed Fe3O4@Tp-PaV@MPBA exhibited high selectivity (improved 2-8 times compared to Fe3O4@Tp-PaV), fast adsorption (equilibration time ≤ 15 min), and large adsorption capacities (19.45 to 36.86 mg/g) for macrolide extraction. Further, adsorption interaction mechanism was comprehensively elucidated by experimental and molecular simulation study, demonstrating Fe3O4@Tp-PaV@MPBA displayed high affinity towards macrolides under interferents, and the dominant interaction was boronate affinity rather than non-covalent forces. Finally, the MSPE-UPLC-MS/MS method was developed and proven to be sensitive (LODs: 0.04-0.50 μg/kg), accurate (recoveries: 73.48-116.48 %), precise (RSDs below 12.78 %) for the determination of macrolides in complex matrices with low matrix effects (-6.81 to 7.68 %).