Synthesis of cobalt-based magnetic nanoporous carbon core-shell molecularly imprinted polymers for the solid-phase extraction of phthalate plasticizers in edible oil

In this work, cobalt magnetic nanoporous carbon (Co-MNPC) is employed as an alternative to intensively used Fe3O4 cores for the preparation of magnetic molecularly imprinted polymers (Co-MNPC@MIPs) for the first time. Co-MNPC was prepared by one-step carbonization of Zeolitic Imidazolate Framework-67 (ZIF-67). Compared with the traditional Fe3O4 core, Co-MNPC showed a high specific surface area and large pore volumes. The prepared adsorbents, which could be rapidly collected from a matrix by external magnetic field, were applied for solid-phase extraction of phthalate plasticizers in edible oil. Several requisite extraction parameters were optimized to achieve desired extraction performance. Under the optimum extraction conditions, Co-MNPC@MIPs displayed better performance than commercialized columns. An analysis method based on Co-MNPC@MIPs coupled with gas chromatography (GC) was established. The linear range was 1–150 μg mL−1, and the detection limit range was 0.010–0.025 μg mL−1. The spiked recovery rate of the five phthalate plasticizers was 81.6–102.2%, with a relative standard deviation of 3.25–12.02%. Finally, the proposed method showed good feasibility for phthalate plasticizer extraction from edible oil.