Magnetic Dispersion Extraction of Tetracyclines Residues from Milk by Chlortetracycline-Imprinted Magnetic Composite Microspheres

A magnetic dispersion extraction method was developed based on a molecularly imprinted magnetic microsphere for fast separation and analysis of tetracyclines residues in milk samples. The molecularly imprinted magnetic microsphere was prepared by inverse emulsion suspension polymerization and synthesis and extraction conditions were optimized for obtaining excellent affinity and high selectivity. The magnetism, covering amount, clean-up of the magnetic microspheres were characterized by vibrating sample magnetometer, thermogravimetric analysis and HPLC. The molecularly imprinted magnetic microspheres were applied to separate tetracycline antibiotics from milk by magnetic dispersion extraction with a good sample clean-up effect. The average recoveries of four tetracycline antibiotics were obtained in the range of 76.4-95.84 % with precision 2.72-6.81 %. The limits of detection and quantitation of the proposed method were in the range of 5.71-11.18 and 19.02-37.28 mu g/kg, respectively. The results indicated that magnetic dispersion extraction of the molecularly imprinted magnetic microspheres was powerful for the food sample pretreatment with high selectivity and simplified procedure.