Detection and adsorption of florfenicol in milk using bifunctional carbon dot–doped molecularly imprinted polymers

Abstract

Detection of florfenicol (FF) residues in animal‐derived foods, as one of the most widely used antibiotics, is critically important to food safety. The fluorescent molecularly imprinted polymer (MIP) was synthesized by surface‐initiated atom transfer radical polymerization technique with poly(glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) microspheres, 4‐vinylpyridine, ethylene glycol dimethacrylate, and FF as the matrix, functional monomer, crosslinker, and template molecule, respectively. Meanwhile, N–S co‐doped carbon dot (CD) was synthesized with triammonium citrate and thiourea as precursors under microwave irradiation at 400 W for 2.5 min and then integrated into FF‐MIP to obtain CD@FF‐MIP. For comparison, non‐imprinted polymer (NIP) without FF was also prepared. The adsorption capacity of CD@FF‐MIP to FF reached 53.1 mg g−1, which was higher than that of FF‐MIP (34.7 mg g−1), whereas the adsorption capacity of NIP was only 17.3 mg g−1. The adsorption equilibrium of three materials was reached within 50 min. Particularly, CD@FF‐MIP exhibited an excellent fluorescence quenching response to FF in the concentration range of 3–50 µmol L−1. As a result, CD@FF‐MIP was successfully utilized to extract FF in milk samples, which were analyzed by high‐performance liquid chromatography. The standard recoveries were 95.8%–98.2%, and the relative standard deviation was 1.6%–4.2%. The method showed the advantages of simple operation, high sensitivity, excellent selectivity, and low cost, and also demonstrated a great application prospect in food detection.