Nickel-carbon nanotubes derived from HOFs and MOFs as coating material of solid-phase microextraction for sensitive...

As persistent organic pollutants, polychlorinated biphenyls (PCBs) pose significant environmental and health risks due to their widespread contamination and bioaccumulation through the food chain. Therefore, the development of sensitive and reliable analytical methods for their accurate determination is critical. In this study, a competitive coordination strategy was employed to transform hydrogen-bonded organic frameworks into hollow metal-organic frameworks (MOFs) via a one-pot solvothermal process, in which metal-ligand coordination bonds played a key role in framework reconstruction. The resulting MOFs were subsequently used as precursors to synthesize nickel-doped hollow carbon nanotubes (nNi-HMCNTs) through pyrolysis. By adjusting the nickel content in the precursor, the pore structure and Ni-related interaction sites of the derived carbon materials were optimized, improving their suitability as solid-phase microextraction (SPME) coatings. When coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS), the optimized 2.4Ni-HMCNTs coating enabled the sensitive determination of PCBs in food matrices. The established HS-SPME-GC-MS/MS method exhibited a wide linear range (0.001-1000 ng·L^-1), low limits of detection (0.33-1.67 pg·L^-1), and high enrichment factors (13897-14787). Furthermore, density functional theory calculations and experimental characterization were combined to elucidate the enrichment mechanism of PCBs on 2.4Ni-HMCNTs. This work provides a competitive coordination-regulated strategy for constructing hollow carbon-based SPME coatings and demonstrates its potential for trace contaminant enrichment in complex food samples.