A quinoxaline-based conjugated microporous polymer-coating for solid phase microextraction of polycyclic aromatic hydrocarbons in environmental sample

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental contaminants with severe ecological toxicity, released via both biogenic and anthropogenic pathways. Ultra-sensitive analytical methods for the quantitative monitoring of trace PAHs in real samples are urgently required, yet preconcentration is indispensable for accurate analysis due to complex environmental matrices and ultra-trace PAH levels. Herein, a quinoxaline-based conjugated microporous polymer(CMP) with a fluffy rod-groove structure and large π-conjugated plane (CMP-1) was synthesized via the Sonogashira-Hagihara coupling reaction and employed as a solid-phase microextraction (SPME) coating material. Two analytical methods, direct immersion SPME (DI-SPME) and headspace SPME (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS) were established for the highly sensitive detection of 8 trace PAHs in environmental samples. Under optimized conditions, the methods exhibited excellent analytical performance: low limits of detection (LODs) of 0.001–0.0051 ng/mL, a wide linear range of 0.036–1200 ng/mL, and good reproducibility with relative standard deviations (RSDs) of 2.8%–14.8%. The applicability and reliability of the methods were validated by analyzing three environmental water samples (artificial lake water, rainwater, Jinlong Lake water) and three soil samples (sugarcane field soil, roadside soil, gas station soil), with recoveries ranging from 81.2%–116.4% for water samples and 70.6%–106.6% for soil samples, respectively. Adsorption mechanism studies revealed that the CMP-1 coating endows efficient PAH extraction via a synergistic effect of its fluffy rod-groove porous structure, large specific surface area, hydrophobic interactions, and molecular size filling effect with PAHs. Furthermore, greenness assessment using four authoritative metrics (GAPI, Complex GAPI, AGREE, AGREEprep) confirmed the good green analytical chemistry characteristics and practical applicability of the proposed methods.