Amide and carboxyl dual-functionalized magnetic microporous organic networks for efficient extraction of cephalosporins

Cephalosporins (CEFs) are a class of widely used toxic antibiotics. Development of a rapid and sensitive method for detecting trace CEF residues in food samples is still challenging. Herein, we report preparation of an amide and carboxyl groups dual-functionalized core-shelled magnetic microporous organic network MMON-COOH-2CONH for efficient magnetic solid-phase extraction (MSPE) of CEFs from milk powder samples. Under optimal conditions, the established MMON-COOH-2CONH-MSPE-HPLC-UV method owns wide linear range (3-10000 µg kg-1), low limits of detection (1-3 µg kg-1), large enrichment factors (93.9-99.4), low adsorbent consumption (3 mg), and short extraction time (6 min). Synergistic extraction mechanisms of ionic bonding, hydrogen bonding, π-π, and hydrophobic interactions were elucidated by both theoretical density functional theory calculations and experimental data. This study confirms that preparation of dual-functionalized MMONs and introduction of ionic groups are feasible to promote MMONs application in sample pretreatment.