Sulphonate functionalized covalent organic framework-based magnetic sorbent for effective solid phase extraction and determination of fluoroquinolones.

Most of the reported covalent organic frameworks (COFs) are hydrophobic, limiting their adsorption application in sample pretreatment field. In this work, sulphonate functionalized magnetic covalent organic frameworks (COFs) composites were first synthesized by loading gold nanoparticles on Fe3O4@COF(TpBD) surface and then functionalized by sodium 3-mercaptopropanesulphonate immobilization via Au-S bonding formation (denoted as Fe3O4@COF(TpBD)@Au-MPS nanocomposites), which were further utilized as adsorbents for magnetic solid-phase extraction (MSPE) of fluoroquinolones. Compared with Fe3O4@COF(TpBD), the composites exhibited higher affinity to fluoroquinolones. Under optimized conditions, the developed MSPE method coupled with HPLC-MS/MS showed good linearity (R2 ≥0.9989) and yielded low limits of detection (0.1-1.0 μg kg-1) for fluoroquinolones. Moreover, the proposed method was successfully applied to extract fluoroquinolones from spiked meats (pork, chicken and bovine). The satisfactory recoveries were in the range of 82-110.2% with the relative standard deviations (RSDs) lower than 7.7%. These results indicated that the Fe3O4@COF(TpBD)@Au-MPS is a promising magnetic adsorbent for trace fluoroquinolones determination in meat samples. This work not only provided a facile strategy for COF functionalization, but also developed an efficient method for detecting fluoroquinolones in foodstuffs.