A magnetic adsorbent of nitrogen-doped graphene quantum dots, zinc metal-organic framework and molecularly imprinted polymer to extract phenylureas

A highly selective composite nano-sorbent was designed and fabricated for the extraction and enrichment of phenylureas. The nano-sorbent was composed of nitrogen-doped graphene quantum dots (N-GQDs), a zinc metal-organic framework (IRMOF-1) and magnetite nanoparticles incorporated in molecularly imprinted polymer (MIP). The fabricated nano-sorbent was characterized and applied to extract and enrich three phenylureas in a dispersive magnetic solid-phase extraction (d-MSPE) process. The developed method was highly sensitive and detected the target phenylureas at trace levels. The linear range was from 1.0 to 150 µg L−1 and the limit of detection was 1.0 µg L−1. The large specific surface area of the nano-sorbent produced highly efficient adsorption. When applied to extract phenylureas in vegetable samples, recoveries were in the range of 80.2–95.8% with relative standard deviations lower than 8.0%. The developed nano-sorbent not only exhibited highly selective and efficient extraction but also good stability which can be reused four times, and ease of fabrication. The developed strategy can also be modified for the extraction and determination of other organic compounds in various complex samples.