Fabrication of highly fluorinated porphyrin-based covalent organic frameworks decorated Fe 3 O 4 nanospheres for magnetic solid phase extraction of fluoroquinolones

A highly fluorinated porphyrin-based covalent organic frameworks magnetic adsorbent (FPy-COF@PDA@Fe 3 O 4 ) was fabricated by using polydopamine (PDA) grafting Fe 3 O 4 nanospheres as magnetic core and FPy-COF as shell for magnetic solid phase extraction (MSPE) of fluoroquinolones (FQs). FPy-COF was constructed by using 5,15-bis(4-aminophenyl)-10,20-bis(perfluorophenyl)porphyrin and 4,4′-biphenyldicarboxaldehyde as two building blocks. PDA as a bridge grafting on the surface of Fe 3 O 4 nanospheres facilitated the growth of FPy-COF. The morphology and structure of FPy-COF@PDA@Fe 3 O 4 adsorbent were characterized in detail. The prepared magnetic adsorbent exhibited good extraction capability to amphiphilic FQs due to their superior chemical affinities such as fluorophilic interaction and hydrogen-bond interaction from nitrogen-rich skeleton. Under the optimized conditions, the MSPE method combined with high performance liquid chromatography with ultraviolet detection (HPLC–UV) was developed to sensitively quantify trace level of six FQs in milk samples. The developed MSPE-HPLC method showed good linearity with wide concentration range, precision, and low limits of detection (S/N = 3) for six FQs as low as 2.3 ngꞏmL −1 in milk. The extraction recoveries of different spiked concentrations were in the range 77.8–110.4% for milk samples with RSD less than 9.7%. Graphical Abstract