Quinoxaline core-conjugated microporous polymer coating for highly sensitive solid-phase microextraction of phthalate esters in liquid food samples

Conjugated microporous polymers (CMPs) have been widely used in various fields as a new class of porous materials. In this study, a quinoxaline-based CMP (BQP-CMP) was prepared and used as the coating in SPME for the extraction and enrichment of nine phthalate esters (PAEs) in juice, soya sauce, cooking wine, and blended edible oil samples. Several parameters affecting solid-phase microextraction (SPME) were optimized. The feasibility of the developed method was verified using real samples, which showed low LODs (0.014–0.032 µg L⁻¹), wide linearities (0.05–50 µg L⁻¹), good repeatability (2.8–6.6%), and a long service life. The real liquid samples were successfully analyzed using this proposed method and spiked recoveries of 70.16–96.36% were obtained. Moreover, the interaction model and binding energies between BQP-CMP and the PAEs were explored using molecular docking. Satisfactory extraction efficiency was achieved owing to the high specific surface area (601.62 m² g⁻¹), high hydrophobicity, and the conjugated planar structural unit distribution of BQP-CMP. This study demonstrates that BQP-CMP is excellent as a rapid and sensitive analysis material for PAEs at trace levels in various types of samples and that CMP materials are also excellent candidates for SPME coatings.