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 (Fe3O4/HCP-COOH) with reverse phase/cation exchange mixed-mode performance was synthesized through a two-stage process: (1) Fabrication of HCP-COOH via FeCl3-catalyzed Friedel-Crafts alkylation using 1,4-phenylenediacetic acid and 1,4-bis(chloromethyl)benzene; (2) In situ growth of Fe3O4 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.