Molecularly imprinted magnetic covalent organic framework for selective extraction of metformin in health products

Selective detection of metformin (Glucophage) as an undeclared adulterant in health products is hampered by the complexity of sample matrices and the limitations of conventional adsorbents. While molecularly imprinted polymers (MIPs) offer specificity, they often suffer from low capacity and slow mass transfer. To overcome these challenges, a hierarchical adsorbent by grafting MIPs onto magnetic covalent organic frameworks (MCOFs) was engineered. MIPs@MCOFs substrate provided extensive surface area for high-density imprinting, while the magnetic core facilitates easy separation. MIPs@MCOFs exhibited high adsorption capacity (55.49 mg/g) and adsorption rate (40 min ) for Met. Based on this material, a reliable MSPE-HPLC method was established. It exhibited a wide linear range (5–10 , 000 μg/L), a low detection limit (1.1 μg/L), and satisfactory precision with intra- and inter-day RSDs below 2.2% and 6.5%, respectively. The method was validated for analyzing real samples, offering a powerful solution for combating illegal pharmaceutical adulteration in the health product industry.