Porous cage-like hollow magnetic carbon-doped CoO nanocomposite as an advanced sorbent for magnetic solid-phase extraction of nine polycyclic aromatic hydrocarbons.

In this study, porous cage-like hollow magnetic carbon-doped CoO nanocomposite (CoO@C) was successfully synthesized using a metal-organic frameworks (MOFs) as precursor by one-step calcination method in this work. The obtained nanoporous composite showed excellent magnetic response by taking advantage of the magnetism of CoO even without the Fe3O4, making it an advanced sorbent for magnetic solid-phase extraction (MSPE). The Co-MOF and CoO@C were characterized by XRD, TGA, SEM, TEM, vibrating sample magnetometry, and FT-IR spectroscopy. Based on this, a method using CoO@C for MSPE coupled with HPLC was established for the analysis of nine polycyclic aromatic hydrocarbons (PAHs) from various real water samples. The amount of sorbent, extraction times, extraction temperature, desorption times, oscillation rate, and elution volume were optimized. Under the optimal conditions, the method had good relative standard deviations (RSDs) of 1.1%-6.5% and a satisfying linearity range of 0.5-1000 μg L-1. The low LOD and LOQ for nine PAHs were found to be 0.06-1.30 μg L-1 and 0.19-4.30 μg L-1, respectively. The experimental results indicated that the prepared nanocomposite showed excellent adsorption capacity compared to other commercial sorbents and has potential applications for the removal of hazardous pollutants from environmental samples.