Magnetic solid-phase extraction for simultaneous enrichment of five types 20 antibiotics based on sulfonic acid-modified hierarchical porous covalent organic framework materials.

Monitoring antibiotic residues in environmental waters is essential for ecological‑risk assessment and public‑health protection. However, simultaneous enrichment of multiple classes of antibiotics is hindered by their distinct physicochemical features, including varied molecular sizes, surface charges and functional groups. In this work, density‑functional‑theory (DFT) calculations guided the rational ligand‑structure design of sulfonic‑acid‑functionalized covalent organic frameworks. The magnetic composite Fe₃O₄@ETTBC‑BD‑SO₃H was synthesized, fully characterized, and employed for magnetic solid‑phase extraction (MSPE) of 20 antibiotics from five chemical families, followed by quantification using UHPLC‑MS/MS. Key MSPE experimental parameters were systematically optimized. The method exhibited good linearity in the ranges of 2.5-1000 ng/L (8 analytes), 5-1000 ng/L (7 analytes), and 10-1000 ng/L (5 analytes), with LODs of 0.09-2.88 ng/L. Validations in tap water, reservoir water and wastewater samples afforded acceptable recoveries (53.6-107.3%). We further analyzed influent‑effluent samples from seven Qingdao wastewater‑treatment plants and carried out corresponding environmental‑risk assessments. Our results highlight the great potential of sulfonated covalent‑organic‑framework materials as magnetically recoverable adsorbents for trace‑antibiotic enrichment in environmental pretreatment workflows.