Nitrogen-rich carbon nitride as solid-phase microextraction fiber coating for high-efficient pretreatment of polychlorinated biphenyls from environmental samples

A two-dimensional nitrogen-rich carbon nitrogen (C3N5) material was prepared via a facile high temperature thermal polymerization. For the first time, the C3N5 was used as fiber coating of solid-phase microextraction (SPME) to extract and preconcentrate polychlorinated biphenyls (PCBs) before gas chromatography (GC) analysis. The X-ray diffraction, N-2 adsorption-desorption, Fourier transform-infrared spectroscopy, thermogravimetric analysis, and X-ray photoelectron spectroscopy were performed to investigate structure, functional groups, thermal stability, bonding type, element composition, and atomic ratio of C3N5. The two-dimensional planar stacking structure was further verified by scanning electron microscopy and transmission electron microscopy. Five PCBs including PCB-4, PCB-12, PCB-29, PCB-52 and PCB-101 were selected as targets to evaluate performance of SPME fiber. Under the optimal conditions, the method showed a good linear range from 0.01 to 1000 ng/mL with the correlation coefficients (R-2 ) higher than 0.9990. Enrichment factors of the method were obtained from 2045 to 3080. The limits of detection (LODs, S/N = 3) and limits of quantification (LOQs, S/N = 10) were calculated as 0.0031-0.0111 ng/mL and 0.01-0.05 ng/mL, respectively. The precisions of intra-day and inter-day were obtained with the relative standard deviations (RSDs) at 1.5-6.6% and 0.8-6.9%, respectively. The fiber-to-fiber producibility was achieved with RSDs ranged from 3.5% to 11.4%. The method was applied to detect PCBs in river water and soil samples. The contents were calculated at 0.040-0.147 ng/mL in water and 0.520-3.218 ng/g in soil. The C3N5 as SPME fiber coating material may be applied to extract and preconcentrate other environmental pollutants which have similar chemical structures with PCBs. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A two-dimensional nitrogen-rich carbon nitrogen (C3N5) material was successfully prepared and applied as fiber coating for solid-phase microextraction (SPME) of polychlorinated biphenyls (PCBs). The method showed good linear range, detection limits, and quantification limits, with successful detection of PCBs in water and soil samples. This study demonstrates the potential of using C3N5 as SPME fiber coating material for extracting and preconcentrating environmental pollutants with similar chemical structures to PCBs.