Antibiotic enrichment in seawater from solid-phase extraction to molecularly imprinted polymers and covalent organic frameworks.

Antibiotic residues in seawater and the associated antibiotic resistance genes (ARGs) pose serious threats to marine ecosystems and human health. Accurate monitoring of antibiotics depends on efficient enrichment, but the high salinity and complex dissolved organic matter in seawater render conventional solid-phase extraction (SPE) susceptible to severe matrix effects and poor selectivity. This review systematically evaluates the limitations of SPE in seawater matrices and examines two emerging high-selectivity materials, molecularly imprinted polymers (MIPs) and covalent organic frameworks (COFs), focusing on their design principles, synthesis strategies and enrichment performance. MIPs achieve high selectivity through template-directed recognition (imprinting factors typically 2-10) but have limited adsorption capacity (20-150 mg/g for conventional MIPs). COFs exhibit excellent adsorption capacity and mass transfer owing to their high specific surface area (>2000 m2/g) but lack sufficient selectivity. Their composite, COF@MIPs, synergistically combines both advantages, with reported 2-5-fold higher adsorption capacity and 40-60% shorter equilibrium time in non-seawater matrices; however, seawater validation remains lacking. This review also summarizes offline and online enrichment coupling strategies with chromatography-mass spectrometry, highlighting the integration of high-selectivity materials into online SPE systems. Future directions should focus on optimizing COF@MIP interfacial synthesis, developing salt-tolerant and antifouling stimuli-responsive materials, integrating them into online SPE systems and standardizing methods, thereby providing key technical support for global marine environmental health monitoring and antibiotic pollution control.