Metal-organic framework-based molecularly imprinted polymers for the dispersive solid-phase extraction of...

The coastal zone is a critical interface between terrestrial and marine systems, providing ecosystem services and economic value while serving as a major sink for land-derived contaminants. The identification and quantification of new pollutants (NPs), particularly antibiotics, even as trace residues, in coastal environments are necessary owing to their potential ecological and human-health risks. Given the complex, high-salinity matrices of samples from coastal zones and their low analyte concentrations, efficient sample pretreatments for cleanup and enrichment are required. Metal-organic framework-based molecularly imprinted polymers (MOF-MIPs), integrating the high porosity and surface area of MOFs with the molecular recognition ability of MIPs, have become promising sorbents for solid-phase extraction (SPE). Herein, a core-shell ZIF-8@MIP composite was facilely synthesized via surface imprinting and one-pot precipitation polymerization using ciprofloxacin (CIP) as the template and the ZIF-8 MOF as the core. The morphology, structure and composition of the composite were well characterized, and the adsorption equilibrium could be reached within 30 min, with a high maximum adsorption capacity of 151.96 mg g^-1. Then, the ZIF-8@MIPs-based dispersive SPE (DSPE) coupled with HPLC-UV was developed for the simultaneous enrichment and determination of six fluoroquinolone antibiotics (FQs) in coastal zone water and biological samples. Under optimized conditions, low limits of detection of 0.060-1.440 μg L^-1 and limits of quantification of 0.201-4.799 μg L^-1 were achieved. Spiked recoveries in beach seawater, aquaculture wastewater, river water, and biological samples (pomfret and prawn) ranged from 92.6% to 118.9%, with relative standard deviations (RSDs) within 0.2%-6.1%. The present DSPE-HPLC study offers a simple and alternative method for NP analysis in coastal samples and could enrich the research scope of MOF-MIP-based sample pretreatment.