Dumbbell-shaped stir bar coated with dendrimer-based MIPs for selective extraction and analysis of vardenafil and its analogue sildenafil in health foods

A novel dendrimer-based molecularly imprinted polymers (MIPs) coated dumbbell-shaped stir bar (DSB) was developed to enrich and analyze two kinds of phosphodiesterase type 5 (PDE-5) inhibitors in health foods (Hfs). The MIPs, with vardenafil as the template molecule and methacrylic acid (MAA) as the functional monomer, were synthesized on the surface of the dendritic-grafting DSB which was filled with magnetic core as substrate. The MIPs-DSB possessed mechanical stability, high adsorption capacity and good selectivity for vardenafil and its analogue sildenafil. A method for the determination of vardenafil and sildenafil in Hfs was established by stir bar sorptive extraction (SBSE) coupled with HPLC-UV. The contents of vardenafil and sildenafil were found to be 3.65 and 2.66 μg g−1, respectively, and the average recoveries in spiked Hfs were 86.5–91.8% with a relative standard deviation (RSD) below 5%. All results revealed that the MIPs-DSB coupled with HPLC-UV could be applied to the highly selective extraction and sensitive determination of trace analytes in a complex matrix.