A new strategy to enhance the enrichment performance of sorbent: Embedding N element into MOF derived carbon materials.

The utilization of an efficient and reliable coating material is of paramount importance for the effective implementation of solid-phase microextraction (SPME) process. For enhancing the adsorption capacity of metal organic framework (MOF) derived carbon materials, in this study, a series of N-doped carbon nanotubes wrapping hollow Ni-MOF-derived carbon sphere (Ni@HC-NCNTs-X) were elaborately designed and synthesized with hollow Ni-MOF as a nutritious platform and by adding dicyandiamide (DCDA) in the one-step pyrolysis processes. The mass ratios of the Ni-MOF and DCDA were optimized, and the obtained materials were used as SPME coating in conjunction with gas chromatography-tandem mass spectrometry (GC-MS/MS) for ultrasensitive determination of polychlorinated biphenyls (PCBs) from beverages. The Ni@HC-NCNTs-5 as coating material exhibited the best enrichment performance and excellent stability based on the unique hollow structure and N-doped active sites. The adsorption mechanism between Ni@HC-NCNTs-5 and PCBs was explored by combining density functional theory (DFT) calculations and experimental characterization. Under optimal conditions, the developed method possessed wide linear ranges (0.2-1000 ng L), low detection limits (0.06-0.10 ng L), and satisfactory recovery rates (71.8-115 %). The results indicated that this work provided an effective synthetic strategy for preparing adsorbents with enhanced enrichment performance for trace organic pollutants.