Preparation And Application Of Magnetic Molecularly Imprinted Solid Phase Extraction Materials

Magnetic molecularly imprinted polymers (mag-MIPs) not only displayed highselectivity and large adsorption capacity toward template molecule, but also can beisolated easily from samples with an external magnet without complicated packingcolumn, centrifugation or filtration step. In this paper, a series of novel magneticimprinted materials based on magnetic carbon materials were prepared and applied inenrichment adsorption of environmental endocrine and antibiotic combined with highperformance liquid chromatography. The mag-MIPs showed higher separation andenrichment ability toward the template molecules. The main contents are as follow:1. A novel magnetic molecularly imprinted polymer based on magnetic graphenecoated with silicon dioxide layer (Fe3O4@GO@MIP) was synthesized using heatedpolymerization technique. The MIP was characterized by transmission electronmicroscopy (TEM), scanning electron microscopy (SEM), Fourier transform-infraredspectroscopy (FT-IR), thermogravimetric analysis (TGA) and vibrating samplemagnetometer (VSM). The results showed a thermal stability magnetic imprinted layerwith the thickness of55~65nm was coated steadily on graphene oxide surface.Adsorption performance of the Fe3O4@GO@MIP was investigated combined withmagnetic solid phase extraction (M-SPE) and high-performance liquid chromatography(HPLC) technology, and the results indicated that the Fe3O4@GO@MIP possessedhigher selectivity towards tetrabromobisphenol A with the maximum adsorptioncapacity of16.33mg/g. The magnetic molecularly imprinted composite material wassuccessfully applied to separation and enrichment of tetrabromobisphenol A inenvironmental water samples combined with high-performance liquid chromatographytechnology.2. A novel magnetic molecularly imprinted polymers based on magnetic multi-walledcarbon nanotubes (MMWNTs-MIPs) was developed for extraction of bisphenol A (BPA)from environmental soil in this paper. The MMWNTs-MIPs were characterized bytransmission electron microscopy, Fourier transform-infrared spectroscopy,thermogravimetric analysis, X-ray diffraction and vibrating sample magnetometer indetail. The results showed a stability magnetic imprinted layer with the thickness of70~100nm was coated on multi-walled carbon nanotubes surface. The propertiesinvolving adsorption dynamics, static adsorption, and selective recognition capacity ofthe MMWNTs-MIPs were evaluated. The MMWNTs-MIPs exhibited good siteaccessibility in which it only took30min to achieve adsorption equilibrium and highlyselective recognition for the template BPA. Adsorption performance of theMMWNTs-MIPs was investigated combined with high-performance liquidchromatography technology, and the results indicated that the MMWNTs-MIPs possessed higher selectivity towards BPA with the maximum adsorption capacity of35.58μmoL/g. The proposed magnetic solid phase extraction procedure was used forthe separation and enrichment of BPA in environmental soil samples successfully withthe recoveries ranging from91.6to101.2%.3. In this paper a novel composite imprinted material based on poly (methylmethacrylate)(PMMA) grafted magnetic multi-walled carbon nanotubes layer wassuccessfully synthesized using erythromycin as the template and methacrylic acid as thefunctional monomer. The magnetic carbon nanotubes molecularly imprinted polymers(mag-MWCNTs-MIPs) were characterized by transmission electron microscopy (TEM),scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR),X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) in detail. Theresults showed a magnetic imprinted layer was coated steadily on the multi-walledcarbon nanotubes surface. The experiments of adsorption dynamics, static adsorption,and selective recognition were conducted to evaluate the adsorption performance. Theresults showed that the mag-MWCNTs-MIPs displayed a rapid dynamic adsorptiontoward erythromycin, which only need30min to achieve adsorption equilibrium withthe maximum adsorption capacity of31.07mg/g. The mag-MWCNTs-MIPs wereapplied to fast enrich and detect erythromycin from fish tissue samples coupled withhigh performance liquid chromatography (HPLC) with the recoveries of82.7%~88.5%.The mag-MWCNTs-MIPs can not only be collected and separated fast by externalmagnetic field, but also have outstanding mechanical properties and specific recognitiontoward erythromycin.4. In this paper, a highly selective sample clean-up procedure combing magneticdummy molecular imprinting with solid-phase extraction was developed for rapidseparation and determination of4-nonylphenol (NP) in the environmental water samples.The magnetic dummy molecularly imprinted polymers (mag-DMIPs) based onmulti-walled carbon nanotubes were successfully synthesized with surface molecularimprinting technique using4-tert-octylphenol as the dummy template andtetraethylorthosilicate as the cross-Linker. The maximum adsorption capacity of themag-DMIPs for NP was52.4mg/g and it took about20min to achieve the adsorptionequilibrium. The mag-DMIPs exhibited the specific selective adsorption toward NPmolecule. Coupled with high performance liquid chromatography analysis, themag-DMIPs were used to solid-phase extract and detect NP in real water samplessuccessfully with the recoveries of88.6%~98.1%.