Determination of tetracycline antibiotics in food using covalent organic frameworks composites-based on magnetic solid phase extraction coupled to HPLC.

Tetracycline antibiotics (TCs) has been widely applied as animal and human medicine for the prevention and treatment of diseases. The unsafe residues of TCs pose serious risks to human health. Development of a rapid and sensitive method for determining TCs residues in environment and food samples is still challenging. Herein, we report the in-situ one-pot self-assembly preparation of core-shell magnetic covalent organic frameworks (Fe3O4@COFs) composites with crystalline structure for efficient magnetic solid-phase extraction (MSPE) of TCs from various samples. Fe3O4@COFs showed good enrichment performance for TCs and excellent recyclability. Under optimal MSPE conditions, the developed Fe3O4@COFs-MSPE-liquid chromatogram method possessed wide linear range (0.80-10000 µg L-1), low limits of detection (0.24-0.30 µg L-1), low adsorbent consumption (5 mg) and short extraction time (10 min). The extraction mechanism of hydrogen bonding, π-π and hydrophobic interactions was investigated by comparison experiment and adequate analysis and characterizations. This work reveals the potential of crystalline Fe3O4@COFs composites in sample pretreatment.