Hierarchical porous MOFs@COFs-based molecular trap solid-phase microextraction for efficient capture of PAHs and adsorption mechanisms

In view of the high toxicity of polycyclic aromatic hydrocarbons (PAHs), rapid adsorption and efficient analytical methods are research topic with practical significance. Herein, an innovative MOFs@COFs-based molecular trap materials were prepared with hierarchical porous core-shell structure and used as solid-phase microextraction (SPME) fiber coating, which combined with high performance liquid chromatography (HPLC) to achieve the efficient separation, capture, and detection for 7 PAHs in real samples. The possible adsorption mechanism was systematically verified and explained. Under the optimized conditions, the method developed in this experiment had a wide linear range (0.005-400 mu gL-1) with a good linear correlation coefficient (R-2 > 0.9984), low detection limits (0.002-0.405 mu gL-1, S/N = 3) and low quantification limits (0.005-1.351 mu gL-1, S/N = 10). The relative standard deviations (RSDs) of individual fibers and different batches of fibers were 0.26-3.64% and 0.40-5.91%, respectively. Besides, the fiber showed higher enrichment capacity and extraction efficiency for PAHs compared to commercial SPME fibers and other material fibers, and exhibited excellent acid-base stability and reproducibility. This work provided a favorable synthetic pathway for the preparation of MOFs@COFs composites by layer-modified assembly synthesis strategy, showed excellent practical applicability as a SPME fiber coating combined with HPLC, and could be realized to provide technical support for future studies on the separation, adsorption, and analysis of PAHs in the petrochemical industrial zone of the Yellow River Basin.