Metal-organic framework grafted with melamine for the selective recognition and miniaturized solid phase extraction of aristolochic acid Ⅰ from traditional Chinese medicine

Aristolochic acid Ⅰ is a nephrotoxic compound and exist in some traditional Chinese medicines at trace level. Up to now, specific enrichment of aristolochic acid Ⅰ remains important procedure and key problem in its analysis. In this study, melamine was proposed as the recognition unit and grafted on the surface of metal-organic framework to fabricate a specific material for aristolochic acid Ⅰ. This material was prepared by using a two-step strategy and the preparation process was optimized. The physical and chemical properties were investigated using scanning electron microscopy, Fourier-transfer infrared spectroscopy, X-ray diffraction and nitrogen adsorption-desorption techniques. Adsorption properties were evaluated by binding experiments. The melamine modified material exhibited a uniform morphology, high specific surface area (460.20 m² g⁻¹), high adsorption capacity (25.57 mg g⁻¹), fast mass transfer rate and excellent selectivity. Further, a specific and sensitive method was established by using this material as adsorbent of mini-solid phase extraction. The limit of detection was as low as 0.02 μg mL⁻¹. Therefore, melamine modified metal-organic framework is an ideal adsorbent for the recognition and enrichment of aristolochic acid Ⅰ.