Magnetic molecularly imprinted polymer for the selective extraction of sildenafil, vardenafil and their analogs from herbal medicines

The successfully developed magnetic molecularly imprinted polymers (MMIPs) toward six synthetic phosphodiesterase type-5 (PDE-5) inhibitors were described. Sildenafil was used as template for the preparation of MMIPs using superparamagnetic core–shell nanoparticle as supporter. The obtained MMIPs were characterized using transmission electron microscope, Fourier transform infrared, X-ray diffraction, and vibrating sample magnetometer. High performance liquid chromatography (HPLC) with diode array detector (DAD) was used for the analysis of target analytes. The application of MMIPs as selective sorbent in the cleanup of herbal medicine samples prior to HPLC offered simple sample preparation. The adsorption capacity and selectivity of prepared MMIPs and magnetic non-molecularly imprinted polymers were investigated. The binding isotherms were obtained for sildenafil and fitted by Freundlich isotherm model. Structurally similar compound of sildenafil and a reference compound protocatechuic acid were used for investing the selective recognition of MMIPs.