Sustainable One-Pot Synthesis of Dual-Mechanism Magnetic HCPs for Classified Extraction of Trace PAHs and Quaternary Ammonium Pesticides in Environmental Waters

Developing efficient and reliable adsorbents with simplified synthesis and mixed-mode performance is crucial for the accurate quantitative analysis of diverse coexisting environmental pollutants. A magnetic carboxylated hypercrosslinked organic polymer (Fe 3 O 4 /HCP-COOH) with reverse phase/cation exchange mixed-mode performance was synthesized through a two-stage process: (1) Fabrication of HCP-COOH via FeCl 3 -catalyzed Friedel-Crafts alkylation using 1,4-phenylenediacetic acid and 1,4-bis(chloromethyl)benzene; (2) In situ growth of Fe 3 O 4 nanoparticles on HCP-COOH through coprecipitation, utilizing FeCl₃ dually as polymerization catalyst and iron precursor to enhance process efficiency and waste minimization. The nanocomposite functioned as a mixed-mode sorbent for magnetic solid-phase extraction (MSPE), integrating dual retention mechanisms to selectively extract hydrophobic polycyclic aromatic hydrocarbons (PAHs) and cationic quaternary ammonium pesticides (QUATs), with subsequent analysis by GC-MS for PAHs and HPLC-MS/MS for QUATs respectively. Following optimization of adsorption pH, eluent composition, and contact time, the method exhibited high sensitivity with limits of detection (LODs) of 0.80-7.93   ng   L⁻¹ for 15 PAHs and 0.02-16.31   ng   L⁻¹ for 4 QUATs. Validation showed satisfactory recoveries of 89.5-98.3% (RSDs ≤11.2%) in snowmelt and 90.4-101.8% (RSDs ≤11.6%) in lake water (n=3), confirming practicality for simultaneous monitoring of hydrophobic and cationic contaminants in complex environmental water, offering significant advantages in multi-residue analysis for environmental monitoring applications.