In this work, carbon dot-decorated graphite carbon nitride composites (CDs/g-C₃N₄) were synthesized and innovatively used as a SPME coating for the sensitive determination of chlorobenzenes (CBs) from water samples, coupled with gas chromatography–mass spectrometry. The CDs/g-C₃N₄ coating presented superior extraction performance in comparison to pristine g-C₃N₄, owing to the enhancement of active groups by CDs. The extraction capacities of as-prepared SPME coatings are higher than those of commercial coatings due to the functions of nitrogen-containing and oxygen-containing group binding, π–π stacking, and hydrophobic interactions. Under optimized conditions, the proposed method exhibits a wide linearity range (0.25–2500 ng L⁻¹), extremely low detection of limits (0.002–0.086 ng L⁻¹), and excellent precision, with relative standard deviations of 5.3–9.7% for a single fiber and 7.5–12.6% for five fibers. Finally, the proposed method was successfully applied for the analysis of CBs from real river water samples, with spiked recoveries ranging from 73.4 to 109.1%. This study developed a novel and efficient SPME coating material for extracting organic pollutants from environmental samples.

Herein, novel, loose, and porous graphite phase carbon nitride/porous carbon (g-C₃N₄@PC) composites were prepared by decorating cellulose nanocrystals (CNCs). The characterization results demonstrate that the as-prepared composites presented high specific surface areas, porous structures, and abundant chemical groups, with the modification of CNCs. In view of the unique advantages, g-C₃N₄@PC was used as the coating material for the solid-phase microextraction (SPME) of organochlorine pesticides (OCPs) in water and juice samples. The g-C₃N₄@PC-coated fibers showed better extraction efficiencies than commercial fibers (100/7 μm PDMS and PA) toward the OCPs, with the enrichment factors of the g-C₃N₄@PC-coated fibers 5–30 times higher than the latter. Using a gas chromatography–mass spectrometry (GC-MS) instrument, the g-C₃N₄@PC-coated fibers exhibited a gratifying analytical performance for determining low concentrations of OCPs, with a wide linear range (0.1–1600 ng L⁻¹ for water; 0.1–1000 ng L⁻¹ for juice), low limits of detection (0.0141–0.0942 ng L⁻¹ for water; 0.0245–0.0777 ng L⁻¹ for juice), and good reproducibility and repeatability in optimal conditions. The established method showed good sensitivity and recovery in the determination of OCPs in the water and fruit juice samples, which displayed broad prospects for analyzing organic pollutants from environmental samples.