Development and application of novel clonazepam molecularly imprinted coatings for stir bar sorptive extraction

The molecularly imprinted magnetic stir bar coatings were created based on graft-functional Fe3O4 nanoparticles with magnetic field-induced self-assembly. The magnetic complex including clonazepam as template, the graft-functional Fe3O4 nanoparticles and methacrylic acid as monomers was pre-assembled through π–π interaction and hydrogen bonding, then was directionally adsorbed on the surface of magnetic stir bar under the magnetic induction. The molecularly imprinted coating with well-ordered structure was generated by one-step copolymerization based on the cross linking of ethylene glycol dimethacrylate. The molecularly imprinted coating with multiple recognition sites could be manufactured and applied in polar solvents, and showed superior selectivity and fast binding kinetics for benzodiazepines. The analytes in herbal health foods, treated by stir bar sorptive extraction, were determined by HPLC-UV. Good linearity was observed in the range of 0.01–2 μg mL−1. The content of clonazepam in the herbal health foods was found to be 44 ng g−1, and the average recoveries were 89.8–103.3% with a relative standard deviation (RSD) <6.5%, demonstrating the successful application in real sample analysis.

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