Synthesis of magnetic mesoporous metal-organic framework-5 for the effective enrichment of malachite green and crystal violet in fish samples

A novel, magnetic and mesoporous Fe3O4@PEI-MOF-5 material was synthesized for the effective enrichment of malachite green (MG) and crystal violet (CV) in fish samples. The Fe3O4@PEI-MOF-5 material was prepared by a facile two-step solvothermal approach in which Fe3O4@PEI and MOF-5 were connected through chemical bonds. Characterization of the newly synthesized Fe3O4@PEI-MOF-5 material was performed by Fourier transform infrared spectroscopy, X-ray diffractometry, vibrating sample magnetometry, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis and X-ray photoelectron spectroscopy. This new material was determined to have high magnetization and chemical stability, a large surface area and a distinctive morphology. An effective enrichment and detection method for MG and CV was subsequently developed by combining the Fe3O4@PEI-MOF-5 material with ultra-high-performance liquid chromatography-tandem mass spectrometry. The linearity ranges of this approach for MG and CV were 1-500 ng/mL and 0.25-500 ng/mL, respectively, with correlation coefficients (R2) of 0.999. The limits of detection (LODs) of the method for MG and CV were 0.30 ng/mL and 0.08 ng/mL, respectively, indicating that the Fe3O4@PEI-MOF-5 material had good adsorption properties for MG and CV. Fe3O4@PEI-MOF-5 can be expected to also provide efficient enrichment of MG and CV in other complex matrices.