Universal carbon nanotubes-polybenzimidazole SPME coating and its application for both gas and liquid chromatography

In this study, we present a novel combination of carbon nanotubes (CNT), widely used as a sorbent material in solid-phase extraction-based methodologies, with polybenzimidazole (PBI), recently introduced as a universal binder for physical immobilization of sorbent particles. This combination was used to prepare CNT-PBI coated solid-phase microextraction (SPME) devices (fibers, arrows, and blades) suitable for both thermal and solvent desorption. The resulting CNT-PBI SPME devices presented excellent mechanical resistance and high thermal stability, capable of enduring multiple thermal desorption cycles without compromising extraction efficiency. They also demonstrated stability in a range of organic solvents commonly used for solvent desorption, with no swelling or shrinkage observed. We evaluated the performance of the CNT-PBI fibers in gas chromatography-mass spectrometry (GC-MS) analysis of BTEX (benzene, toluene, ethylbenzene and xylene) compounds, comparing them to carboxen/polydimethylsiloxane (CAR-PDMS) and CAR-PBI fibers. The CNT-PBI fibers showed superior extraction efficiency for benzene, toluene, and xylene. In liquid chromatography-mass spectrometry (LC-MS) analysis of drugs of abuse, CNT-PBI blades outperformed CNT blades prepared with a conventional polyacrylonitrile (PAN) binder in extracting non-polar drugs (log P > 2.8). Moreover, CNT-PBI blades demonstrated similar extraction performance to C18-PBI blades, considering the differences in particle-to-binder ratio and the coating thickness of each material. Comparing the extraction performance between CNT-PBI and CNT-PAN blades for liquid chromatography-high resolution mass spectrometry (LC-HRMS) untargeted analysis in water samples revealed that the binders (PBI and PAN) significantly influenced the sorption capabilities of the coating particles. These findings highlight the potential of solvent and thermally stable CNT-PBI devices for SPME in both GC and LC analyses.