Covalent Organic Framework/Reduced Graphene Oxide Composite for Solid-Phase Microextraction of Polycyclic Aromatic Hydrocarbons in Honey

A covalent organic framework/reduced graphene oxide composite (COF/rGO) was fabricated by facile ultrasonic self-assembly strategy and further coated onto stainless-steel wire by physically adhesion for headspace solid-phase microextraction (HS-SPME) of polycyclic aromatic hydrocarbons (PAHs) prior to their determination by gas chromatography-flame ionization detection (GC-FID). Compared with the individual porphyrin-based COF and GO, the as-prepared COF/rGO composite effectively prevented the stacking of GO nanosheets and exhibited enhanced extraction efficiency due to the synergistic effect, with the enrichment factor up to 8816 for phenanthrene. The morphology, structure, and stability of COF/rGO composite was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, and N-2 adsorption-desorption. Effective adsorption and desorption parameters including extraction temperature, extraction time, desorption temperature, desorption time, agitation speed, and ionic strength were optimized. The established HS-SPME/GC-FID method based on COF/rGO composite fiber was evaluated in terms of linear ranges from 0.5 to 250.0 ng mL(-1) with R-2 >= 0.9985, limits of detection in the range of 0.09-0.59 ng mL(-1), and limits of quantitation in the range of 0.31-1.97 ng mL(-1). The intra-day, inter-day, and fiber-to-fiber relative standard deviations (RSDs) were in the range of 1.86-4.37%, 2.48-5.40%, and 3.51-7.81%, respectively. The established method was employed to determine trace level of PAHs in honey with good recoveries (62.99-128.8%) and reliable reproducibility (0.51-7.63%).