Preparation of polydopamine‐coated, graphene oxide/ Fe 3 O 4 ‐ imprinted nanoparticles for selective removal of sulfonylurea herbicides in cereals

BACKGROUND Sulfonylureas are potentially toxic broad‐spectrum herbicides. They pose a persistent threat to food safety and the environment. It is therefore important to develop a rapid and efficient pretreatment and detection method to prevent their harmful effects on human health. RESULTS In the present work, a novel and highly selective absorbent for chlorosulfuron (CS) detection was prepared by the simple self‐polymerization of dopamine on the surface of magnetic graphene oxide using a CS template. The resultant imprinted nanoparticles (MGO@PDA‐MIPs) were characterized by transmission electron microscopy, X‐ray diffraction, vibrating‐sample magnetometry, thermogravimetric analysis, and nitrogen adsorption–desorption. The adsorption experiments demonstrated that the MGO@PDA‐MIPs have excellent selectivity with regard to CS, with a high imprinting factor of 3.41 compared with a non‐imprinted polymer. The nanoparticles rapidly achieve adsorption equilibrium and efficient desorption because there are numerous binding sites on the thin polydopamine imprinting layer. Under optimized conditions, the MGO@PDA‐MIPs can be used to detect sulfonylurea residues in cereal samples by magnetic solid phase extraction coupled with high performance liquid chromatography (HPLC). The nanoparticles have a satisfactory recovery rate (80.65–101.01%) with a relative standard deviation (RSD) of less than 7.15%, and a limit of detection with regard to CS of 1.61 μg kg −1 (S/N = 3). They can also be re‐used at least seven times. CONCLUSION The MGO@PDA‐MIPs have outstanding recognition performance, and can be prepared by a facile, single‐step, and environmentally friendly process. They therefore have excellent potential for the recognition and separation of trace sulfonylurea herbicides in complex matrices. © 2020 Society of Chemical Industry