Preparation Of Surface Dummy Molecularly Imprinted Sorbents And Its Application For Solid-phase Extraction Of Bisphenol A

Two types of novel suface molecularly imprinted composites were prepared via a dummy template imprinting strategy for solid-phase extraction of bisphenol. Firstly, a covalent template-monomer complex（BPAF-Si） was synthesized according to our previous method using 2,2-bis（4-hydroxyphenyl）hexafluoropropane（BPAF） as the template molecule and 3-（triethyloxysily）propyl isocyanate as the functional monomer. Then, two types of composite sorbents（SiO₂@MIP and QW@MIP） were obtained by synthesizing dummy template imprinted film coated on the suface of silica particles（Si O2） or quartz wool（QW） via the gelation of BPAF and tetraethoxysilane under acidic condition followed by thermal removal of template. The new sorbents were characterized by FT-IR spectroscopy, thermo-gravimetric analysis, nitrogen adsorption-desorption isotherms, and scanning electronmicroscope. Results showed that the nano-thickness imprinted films were formed on the surface of substrates, which is beneficial to the adsorption kinetics of analytes. The static binding tests vertified that the imprinted composites had much higher recognition abilities for BPA than the non-imprinted composites, and the kinetic adsorption tests presented the fast binding kinetics of the surface imprtinted composites for BPA. When used as SPE sorbents, the imprinted composites showed high extraction efficiencies and high enrichment factors for BPA. Based on the two types of imprinted composites, two SPE-HPLC-UV methods were developed and successfully applied to the detection of BPA in BPA-spiked lake water, tap water, drinking water and orange juice samples with recoveries of 96.7-106.0%, RSD of less than 4.0%（n=3）, and limit detections（3S/N） of 0.3 ng/mL. The new surface dummy molecularly imprinted sorbents completely avoided the interference of the residual template molecules and greatly improved the binding kinetics of the target molecules. Therefore, they can be used as good sorbents for SPE of BPA in real samples.