Synthesis of molecularly imprinted polymers via ring-opening metathesis polymerization for solid-phase extraction of bisphenol A
College of Chemistry and Molecular Engineering, Peking University, Beijing, China.Analytical and Bioanalytical Chemistry (Impact Factor: 3.44). 07/2011; 401(4):1423-32. DOI: 10.1007/s00216-011-5178-x
The use of molecularly imprinted polymers (MIPs) prepared by ring-opening metathesis polymerization (ROMP) for bisphenol A (BPA) was reported in this article. The resulting MIPs have high imprinting and adsorption capacities, and can be used for separation and determination of BPA in environmental water samples. The successful application of ROMP in the molecular imprinting field is described here. For the first time, two cross-linkers (dicyclopentadiene and 2,5-norbornadiene) and two Grubbs catalysts (first and second generation) were investigated to compare their effects on the binding performance of MIPs. The ROMP technique is able to create the imprinted polymers within 1 h under mild conditions. Furthermore, it can provide MIPs with obvious imprinting effects towards the template, very fast template rebinding kinetics, high binding capacity and appreciable selectivity over structurally related compounds. The adsorption process for MIPs in this study can be completed within 45 min, which is much faster than that of bulk MIPs synthesized by traditional free-radical polymerization. The resulting imprinting polymer was evaluated for its use as a sorbent support in an off-line solid-phase extraction approach to recover BPA from diluted aqueous samples. The optimized extraction protocol resulted in a reliable MISPE method suitable for selective extraction and preconcentration of BPA from tap water, human urine and liquid milk samples. This article demonstrates the practical feasibility of the MIPs prepared via ROMP as solid-phase extraction materials.
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ABSTRACT: A group of molecularly imprinted polymer (MIP) with specific molecule identification properties for norfloxacin (NFA) was prepared by precipitation polymerization using norfloxacin-Zn2+ as template molecule, ethyleneglycol dimethacrylant as the cross-linker, methacrylic acid and 4-vinyl pyridine as functional monomer respectively. The coordination proportion of the template molecule and functional monomer was studied by ultraviolet spectrum and the characterization of the molecularly imprinted polymer can be achieved by the infrared spectrum analysis. The result indicated that dominant induction imprinted complex with the ratio 1:1 was formed between norfloxacin-Zn2+ and methacrylic acid, while the dominant conjugation imprinted complex was formed by 4-vinyl pyridine as the functional monomer with the ratio of 1:2, and the ChemDraw pictures were used to display the imprinted form of the polymers. Then the scanning electron microscopy and the particle size distribution were used to characterize the physical properties of the molecularly imprinted polymer, the result showed irregular holes and porous scattered in the prepared molecularly imprinted polymer and the non-imprinted polymer surface was dense with no holes, then the particle size of the prepared polymer was less than 100 μm and the average particle size was 39 μm. The adsorption ability of the prepared polymer were researched by the isothermal combined experiment and the result revealed that the prepared molecularly imprinted polymer using 4-vinyl pyridine with the ring space structure as the functional monomer showed better selectivity recognition ability for norfloxacin than methacrylic acid with the chain structure, the specificity adsorption was 66.84 μmol/g and the imprinted index was 4.207, and it also showed better selective ability in the nofloxacin-Zn2+ and ofloxacin-Zn2+ mixture solution, the recognition factor was 3.408. Meanwhile the selective experiment displayed that the adsorption capacity of the non-imprinted polymer was small and closed to each other, therefore the recognition factor was close to 1, this indicated that the recognition ability of the non-imprinted polymer to the adsorption substrate was non selective. © 2012 Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences.Acta Chimica Sinica -Chinese Edition- 03/2012; 70(14):1569. DOI:10.6023/A12030065 · 1.43 Impact Factor
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ABSTRACT: A new dummy template molecule, N,N’-bis(3-vinylbenzylidene)-4,4′-diaminodiphenylmethane (VB-DADPM) was designed to synthesize dummy template imprinted polymer (DIP) for Bisphenol A (BPA). Since the Schiff-base part of VB-DADPM is easily cleaved by a weak acid treatment, the DADPM moiety can be removed after the co-polymerization with crosslinkers. After the post-imprinting oxidation□was carried out to transform the residual aldehyde to carboxylic acid, binding sites toward BPA were generated only inside the binding cavity, which had an estimated binding constant of 1.3 × 10 M, and could recognize the difference between similar molecules BPA and BPB, the latter of which has an ethyl group instead of a methyl group at the central part of BPA.Analytical Letters 07/2012; 45(10). DOI:10.1080/00032719.2012.673099 · 1.03 Impact Factor
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ABSTRACT: A new absorbent (polymer) for solid-phase extraction of ractopamine (RAC) was synthesized on the multi-walled carbon nanotubes (MWCTs) using grafting technique and surface imprinting methods. The superficial characteristics of the polymer were studied by scanning electron microscopy (SEM) and UN spectrometry was applied to investigate the static and kinetic adsorption capacity of the new absorbent. After the experimental conditions for the solid-phase extraction of RAC were optimized, a sensing system for the determination of RAC was established by connecting the solid-phase extraction column with a portable amperometric sensing system. The SEM study showed that numbers of imprinted micro-pores were exhibited on the surface of the imprinted polymers, and the absorption experiments indicated that the molecularly imprinted absorbent possessed satisfactory kinetics for the adsorption of ractopamine. The current response of the amperometric sensor demonstrated a linear correlation to the concentration of RAC over the range of 50 to 450 nM (r = 0.998) and the detection limit was 15 nM. Satisfactory sensitivity and stability was also presented under the optimized experimental conditions. The recoveries of RAC samples reached 87.3–94.8% in urine sample.Analytical Letters 08/2012; 45(12):1736-1748. DOI:10.1080/00032719.2012.677781 · 1.03 Impact Factor
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