Using a Dopamine‐Modified Magnetic Nano‐flower Material for the Solid Phase Extraction of Cyromazine and Melamine in Food Samples

Abstract This work reported a simple method to prepare MGO@PDA@MoS 2 nano‐flower by in situ growth of MoS 2 on the poly‐dopamine (PDA) modified Fe 3 O 4 @GO (MGO) nanosheets. The novel material was composed of PDA modified MGO nanosheets and flower‐like MoS 2 microspheres which two‐dimension ultrathin MoS 2 nanosheets were grown in situ on the surface of MGO@PDA and self‐assembled. The material could be used as a new adsorbent for magnetic solid phase extraction (m‐SPE). The nano‐composite was characterized by TG, VSM, SEM, TEM, XRD, XPS and FT‐IR. The extraction parameters were investigated, including initial concentration, extraction time, pH, ionic strength and desorption conditions. The adsorption behaviors of the material were explored via isotherm and kinetic adsorption experiments, which demonstrated that Langmuir adsorption isotherm model and pseudo‐second‐order kinetic model were more appropriate to describe the adsorption process on MGO@PDA@MoS 2 . A rapid, safe, sensitive, easy, and effective method has been developed for detecting cyromazine and melamine simultaneously in real samples including beef, protein powder and milk by combining with HPLC. Under optimized conditions, the proposed method has a good trueness, wide linear range of 0.1‐100 μg mL −1 , low limits of detection (LOD), satisfactory repeatability and reproducibility. Excellent recoveries for the determination of cyromazine and melamine were obtained in spiked real samples. In a word, the nano‐composite material has the advantages of magnetic separation and high adsorption affinity for cyromazine and melamine, and it is a promising adsorbent for extracting cyromazine and melamine from real samples.