Analysis of tetracyclines from milk powder by molecularly imprinted solid-phase dispersion based on a metal-organic framework followed by ultra high performance liquid chromatography with tandem mass spectrometry.

A novel molecularly imprinted polymer that could selectively recognize tetracyclines in milk powder was synthesized using a metal-organic framework as a support material, tetracycline as template molecule, and 3-aminophenylboronic acid as a functional monomer and a cross-linking agent. The novel molecularly imprinted polymer was characterized by Fourier transform infrared spectrometry, transmission electron microscopy, X-ray diffractometry, thermogravimetric analysis, and N2 adsorption/desorption measurements. The adsorption isotherms, adsorption kinetics, adsorption thermodynamics, and selective adsorption experiments of the novel molecularly imprinted polymer to tetracycline were also studied. The novel molecularly imprinted polymer was used as dispersant of matrix solid-phase dispersion to extraction tetracyclines. After that, the tetracyclines extracted from milk powder were determined by ultra high performance liquid chromatography with tandem mass spectrometry. Under the optimal conditions, the detection limits of tetracyclines were 0.217-0.318 ng/g. The relative standard deviations of intra- and interday precision ranged from 3.8 to 6.9% and from 2.8 to 7.4%, respectively. In all three concentration levels (1.0, 10, 50 ng/g), the recoveries of tetracyclines ranged from 84.7 to 93.9%. The method was successfully applied to the determination of tetracyclines in milk powder.