Preparation and applications of sulfonated hyper-crosslinked polymers for capture and enrichment of fluoroquinolones

This study synthesized a sulfonated hyper-crosslinked polymer, BpBCMBP‑SO₃H, via Friedel-Crafts alkylation and post-sulfonation for the adsorptive removal and enrichment of trace fluoroquinolone antibiotics (FQs) from complex matrices. The material, rich in sulfonic acid groups, exhibited rapid, high-capacity, and selective adsorption towards FQs, with maximum adsorption capacities of 924, 958, 889, and 848 mg·g^-1 for ofloxacin, lomefloxacin hydrochloride, enrofloxacin, and difloxacin hydrochloride, respectively, ranking among the top-tier of previously reported results for FQ adsorption. The adsorption process is predominantly governed by electrostatic interactions, with synergistic contributions from hydrogen bonding, π-π interactions, and hydrophobic interactions. Removal efficiencies of four FQs from aqueous solutions exceeded 95% within 1 min, and reached equilibrium within 10 min with removal efficiencies exceeding 97%. After five consecutive adsorption-desorption cycles, the material retained approximately 70% of its removal efficiency, indicating good reusability. The material was also used for enrichment of FQs in complex matrices. When coupled with high performance liquid chromatography, the detection of low concentration removal rate as low as 10 ng·mL^-1, can be achieved through separation and enrichment in pure water and lake water. In complex matrices such as eggs and milk, the established analytical method exhibited recoveries of 89.3-116.6% for FQs, with intra-day and inter-day relative standard deviations (RSD) below 15%, and the detection limits ranging from 0.33 to 1.67 ng·mL^-1, which underscores its applicability and reliability. This work offers a novel material and reliable methodology for the analysis of trace FQs in environmental and food safety monitoring.