Binary Functional Monomers Research Articles

Improved compatibility of PLA/Starch blends with Binary functional monomers through UV-induced reactive extrusion

In this work, we chose starch as a biomass nucleating agent for PLA to enhance the crystalline properties without affecting the biodegradability of the composite. Under the synergistic effect of glycidyl methacrylate (GMA) and trimethylpropane triacrylate (TMPTA), biodegradable PLA/Starrch composites were prepared by a unique UV-induced reactive extrusion technique. GMA was grafted onto PLA with the help of TMPTA and the modified PLA enhanced compatibility with starch via epoxidation reaction during extrusion. The rheological properties, mechanical properties, and crystallization behavior of PLA/Starch composites were researched. The rheological and FITR results demonstrated that the introduction of GMA/TMPTA in PLA/Starch blends not only promoted the reactive compatibilization of PLA with starch but also produced a certain degree of chain branching effect. Meanwhile, starch provides heterogeneous nucleation sites for PLA crystallization, which improved the crystallization performance of PLA. In addition, the mechanical properties of the composite were improved. Compared with pure PLA, the tensile stress of the composite was increased by 116% and the elongation at break was increased by 118%. In summary, this work provides a new strategy for the preparation of PLA/starch composites, which is expected to expand the application of PLA in the packaging field.

Surface ion-imprinted brewer’s spent grain with low template loading for selective uranyl ions adsorption from simulated wastewater

Efficient removal of uranyl ions from wastewater requires excellent selectivity of the adsorbents. Herein, we report a new strategy using a high monomer/template molar ratio of 500:1 to prepare surface ion-imprinted brewer’s spent grain (IIP-BSG) for selective U(VI) removal using binary functional monomers (2-hydroxyethyl methacrylate and diethyl vinylphosphonate) with high site accessibility and easy template removal. IIP-BSG exhibits a maximum U(VI) adsorption capacity of 165.7 mg/g, a high selectivity toward U(VI) in the presence of an excess amount of Eu(III) (Eu/U molar ratio = 20), a good tolerance of salinity, and a high reusability. In addition, mechanism studies have revealed electrostatic interaction and a coordination of uranyl ions by carboxyl and phosphoryl groups, the predominant contribution of high-energy (specific) sites during selective adsorption, and internal mass transfer as the rate-controlling step of U(VI) adsorption. Furthermore, IIP-BSG shows great potentials to separate U(VI) from lanthanides in simulated nuclear wastewater (pH0 = 3.5) and selectively concentrate U(VI) from simulated mine water (pH0 = 7.1). This study proves that the ion-imprinting effect can be achieved using a very low template amount with reduced production cost and secondary pollution, which benefits large-scale promotion of the ion-imprinted materials for selective uranyl ions removal.

Study of the Preparation and Properties of Chrysin Binary Functional Monomer Molecularly Imprinted Polymers.

Chrysin is a natural bioactive molecule with various groups, and it has been a challenge to separate and enrich chrysin from natural products. Molecularly imprinted polymers have been widely used in the extraction of natural products, but the number and type of functional monomers limits the separation effect. The synergistic action of multiple functional monomers can improve the separation effect. In this paper, molecularly imprinted polymers (Bi-MIPs) were prepared using methacrylic acid and acrylamide as binary functional monomers for the separation and enrichment of chrysin. The Bi-MIPs were characterized using thermogravimetric analyzer (TGA), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). The performances of Bi-MIPs were assessed, which included adsorption isotherms, selective recognition and adsorption kinetics. The experimental results show that Bi-MIPs are shaped as a uniform sphere with an abundant pocket structure on its surface. The adsorption of chrysin on the Bi-MIPs followed a pseudo-second-order and adapted Langmuir–Freundlich isotherm models. The adsorption performance of the Bi-MIPs was determined at different temperatures, and the Bi-MIPs showed excellent adsorption performance at 30 °C. The initial decomposition temperature of the Bi-MIPs was 220 °C. After five times of adsorption and desorption, the adsorption performance of the Bi-MIPs decreased by only 7%. In contrast with single functional monomer molecularly imprinted polymers (Si-MIPs), the Bi-MIPs showed excellent specificity, with an imprinting factor of 1.54. The Bi-MIPs are promising materials in the separation and enrichment of chrysin for their high adsorption capacity, low cost and being environmentally friendly.

Improving identification of molecularly imprinted monolith to benzoylation modified peptides by a deep eutectic solvents monomer-induced cooperation

In this study, a strategy of improving imprinting performance was developed using an enhanced cooperation effect of functional monomers based on deep eutectic solvents (DESs) monomer for the specific enrichment of benzoylation modified peptides. Zinc acrylate and DESs monomers were used as binary functional monomers, and ethylene glycol dimethacrylate was used as the cross-linking agent with SGRGKbz as template to prepare an imprinted monolith. It was observed that the use of DESs monomer significantly improveed the affinity of benzoylation imprinted monolith and increased the adsorption capacity. Under optimal conditions, the recovery and imprinting factor (IF) of the imprinted monolith for SGRGKbz can reach 93.0% and 10.58, respectively. The average recovery of SGRGKbz extracted from the spiked histone digestion solution can reach 88.4% (n = 5, RSD = 3.4%). After treatment with the benzoylation imprinted monolith, 12 benzoylation modified peptides, 13 benzoylation modified sites and 12 benzoylation proteins could be identified in the digestion of mouse liver protein, while only one of each benzoylation modified peptide, benzoylation modified site and benzoylation protein could be identified in the untreated digestion of mouse liver protein. The results indicated that the prepared imprinted monolith using DESs-based functional monomer was an effective method to increase the affinity of the resulting MIP.

Preparation of arctiin moleculary imprinted polymers with 4-vinylpyridine and Allyl-β-cyclodextrin as binary monomers under molecular crowding conditions

This paper reported a feasible method to prepare molecularly imprinted polymer (MIPs) using 4-vinylpyridine (4-VP) and Allyl-β-cyclodextrin (β-CD) as binary functional monomer in the presence of polystyrene (PS). This is the first time that a surrounding of macromolecular crowding was established to improve the imprinting effect of cyclodextrins as monomer in organic solvents. The morphological and characteristics of the polymers with macromolecular crowding reagents were investigated by scanning electron microscope (SEM), fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and nitrogen adsorption experiments. The MIPs were synthesized with 4-VP and β-CD as binary functional monomers, a series of experiments were conducted to compare with the control groups. Furthermore, the selectivity of MIP for analogues experiment showed that the β-CD/4-VP MIP has higher specific recognition for arctiin than β-CD/4-VP NIP. A purification method by β-CD/4-VP MIPs coupled with macromolecular crowding reagents was developed for extraction arctiin from Arctium lappa L. In the MIP-SPE process, the optimal washing and eluting reagents are methanol/water (5:5) and methanol/acid (9:1), respectively. When using the β-CD/4-VP MIPs as SPE absorbent, the mean recoveries for arctiin were 87% with purity of 95%. All the results indicate that this synthetic method using 4-VP and β-CD as binary functional monomers in the presence of PS is a promising method for the preparation of selective adsorbents for arctiin analysis in Arctium lappa L.

Improving sorption performance of amolecularly imprinted monolithic column by doping mesoporous molecular sieve SBA-15.

For the first time a hybrid molecularly imprinted polymer (MIP)doped with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS)-modified mesoporous molecular sieve SBA-15 for target peptide recognitionhas been developed. Zinc acrylate and methacrylic acid were used as binary functional monomers, and ethylene dimethacrylate was used as cross-linking agent to prepare animprinted monolith against Val-Tyr-Ala-Leu-Lys(glutarylation) (VYALKglu). The morphology of the polymers was characterized by scanning electron microscopy, FT-IR spectroscopy, energy dispersive spectroscopy, and 1H NMR. The SBA-15-MPS MIP showed high recovery of 87.1% and the IF of 12.9 for the enrichment of the template peptide. When the template peptide concentration ranged from 5 to 90μgmL-1, the correlation coefficients (R2) for the calibration function obtained was better 0.999. The limit of detection (LOD, 0.30μgmL-1) and limit of quantification (LOQ, 1.0μgmL-1) were achieved for signal-to-noise ratios of 3:1 and 10:1, respectively. When other kinds of synthetic peptides were used as analogs, the selectivity of the SBA-15-MPS MIP was much better than the SBA-15-MPS NIP (without template peptides)with relative selectivity coefficients of 52.8-265. In contrast, little quinolones and biogenic amines areadsorbed with the SBA-15-MPS MIP. The SBA-15-MPS MIP could enrich VYALKglu from spiked histone digestion with the average recovery of 87.8% and the relative standard deviation (RSD) of 0.99%. As a conclusion, doping of SBA-15 is an effective approach to the improvement of performance of molecularly imprinted monolith.

Rapid polymerization of polyhedral oligomeric siloxane-based zwitterionic sulfoalkylbetaine monolithic column in ionic liquid for hydrophilic interaction capillary electrochromatography

A novel polyhedral oligomeric siloxane (POSS)-based zwitterionic monolithic capillary column was prepared via one-pot polymerization in ionic liquid porogen, using N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl)ammonium betaine (DMMSA) and methacrylic ethyl trimethylammonium chloride (META) as binary functional monomers, and methacryl substituted POSS as cross-linker. The pore structure, permeability and homogeneity were well tuned by optimizing the polymerization conditions. The resultant monolith was characterized by scanning electron microscopy, nitrogen adsorption/desorption isotherm and Fourier transform infrared spectroscopy. The incorporation of zwitterionic ligand (DMMSA), quaternary amine group (META) and rigid POSS skeleton endows the hybrid organic-silica monolith with high hydrophilicity, electrostatic interaction and good mechanical stability, as well as a tunable electroosmotic flow over wide pH range. A close investigation of capillary electrochromatographic separations of different types of polar compounds such as bases, nucleosides and benzoic acids on such stationary phase exhibited a retention independent column efficiency up to 118,000 plates/m (thiourea), as well as a mixed-mode hydrophilic interaction chromatography (HILIC) retention mechanism including weak electrostatic interaction, hydrophobic interaction and anion exchange.

A novel electrochemical sensor based on molecularly imprinted polymer with binary functional monomers at Fe-doped porous carbon decorated Au electrode for the sensitive detection of lomefloxacin

A novel molecularly imprinted polymer (MIP) electrochemical sensor for the sensitive detection of lomefloxacin (LFX) was developed for the first time. For this, Fe-doped porous carbon (Fe-PC) was firstly synthesized and then used to modify the Au electrode. MIP film with binary functional monomers was fabricated on the Fe-PC modified Au electrode surface by electropolymerization, with LFX as template molecule, o-phenylenediamine (o-PD) and β-cyclodextrin (β-CD) as binary functional monomers. The results showed that the developed sensor exhibited high selectivity and sensitivity in detection of LFX, which was attributed to the large specific surface area, rich porosity and good catalytic property of Fe-PC, as well as high selectivity and affinity of MIP prepared with binary functional monomers. Under the optimal conditions, the current response was linear to the concentration of LFX ranging from 1 to 120 nM, with a detection limit of 0.2 nM (S/N = 3). Moreover, the developed sensor showed good reproducibility and stability toward LFX detection, and it was applied to detect LFX in water and milk samples with good recoveries ranging from 86.6% to 105.0%.

Synthesis and evaluation of molecularly imprinted polymers with binary functional monomers for the selective removal of perfluorooctanesulfonic acid and perfluorooctanoic acid

This work describes a novel method for the synthesis of molecularly imprinted polymers (MIPs) using 2-(trifluoromethyl) acrylic acid (TFMAA) and 4-vinyl pyridine (4-Vpy) as binary functional monomers, perfluorooctanoic acid (PFOA) as template, and ethyleneglycol dimethacrylate (EGDMA) as cross-linker in the presence of azobisisobutyronitrile (AIBN). The binary functional monomer MIPs were applied to selective recognition for PFOA and perfluorooctanesulfonic acid (PFOS) from aqueous environment. The MIPs were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and microscopic electrophoresis. Thereafter, the adsorption capacity and selectivity of the synthesized MIPs for PFOA and PFOS were evaluated by batch adsorption experiments. The maximum adsorption capacities of the MIPs for PFOA and PFOS were 6.42 and 6.27mg/g, respectively. It was also found that the adsorption capacities remained constant with increasing the solution pH in the range of 2.0-5.0, and then decreased when the pH was further increased. Finally, the novel MIPs can be reused after five cycles of adsorption-desorption-adsorption with no significant decrease of removal rate and have an effective performance in selective removal of PFOA and PFOS in real lake water samples. All the results indicate that the binary functional monomer MIPs have great potential to remove PFOA and PFOS in aqueous environment.

A novel electrochemical sensor based on gold nanoparticles and molecularly imprinted polymer with binary functional monomers for sensitive detection of bisphenol A

In this paper, a novel molecularly imprinted electrochemical sensor was developed for the determination of bisphenol A (BPA). Au nanoparticles (AuNPs) were modified onto the surface of a glassy carbon electrode (GCE) by electrodeposition method. BPA was used as the template molecule, while 4-aminothiophenol (4-ATP) and chitosan (CS) were used as the binary functional monomers. After 4-ATP was modified on the AuNPs by self-assembly, electropolymerization was carried out by cyclic voltammetry (CV) in the presence of CS and BPA to produce molecularly imprinted polymers (MIPs). The prepared sensor was denoted as MIPs/AuNPs/GCE. The morphologies of the electrodes were characterized by scanning electron microscopy (SEM). The MIPs were characterized by Fourier transform infrared spectroscopy (FT-IR). The electrochemical performance of the imprinted electrochemical sensor was investigated by cyclic voltammetry and electrochemical impedance analysis (EIS) techniques in detail. The experimental results showed that the gold nanoparticles could increase the conductivity of the MIPs significantly. The imprinted electrochemical sensor was successfully applied to determine BPA by linear scan voltammetry (LSV). Under the optimal condition, the oxidation peak currents of BPA exhibit a well linear relationship toward the BPA concentrations in the range from 1.5×10−8molL−1 to 5.5×10−5molL−1, with a detection limit of 1.1×10−9molL−1 (S/N=3) and a correlation coefficient of 0.9996.The sensor possesses good stability, selectivity and high sensitivity to BPA, which was successfully applied to detect BPA in actual samples such as plastic and milk. The recoveries were in the range of 97.6–106.5%.

Preparation of core-shell magnetic molecular imprinted polymer with binary monomer for the fast and selective extraction of bisphenol A from milk

In the current study, a new strategy for the extraction of bisphenol A (BPA) from milk has been employed by using surface-imprinted core-shell magnetic beads, prepared by the reversible addition-fragmentation chain transfer (RAFT) polymerization. In order to obtain highly selective recognition cavities, an enhanced imprinting method based on binary functional monomers, e.g. 4-vinylpyridine (4-VP) and β-cyclodextrin (β-CD), was chosen for BPA imprinting. The morphological and magnetic properties of the Fe3O4-MIP beads were characterized by Transmission Electron Microscopy (TEM), Fourier Transform Infrared (FT-IR) Spectroscopy, Thermogravimetric Analysis (TGA), and Vibrating Sample Magnetometer (VSM). The characterization results suggested that MIP was synthesized evenly on Fe3O4-SiO2 surface. The adsorption experiments revealed that Fe3O4-MIPs showed better extraction capacity and selectivity toward BPA and its analogues than the non-imprinted polymers (NIPs). The saturation capacity of Fe3O4-MIP was 17.98mg/g. In milk samples, the present method displayed a lower the detection thresholds, down to 3.7μg/L. The recoveries of BPA in milk samples for three concentrations were found to be within 99.21%, 98.07% and 97.23%, respectively to three concentrations: 1.0μmol/L, 10.0mol/L, 100.0μmol/L. Thus, the MIPs can be used for remove BPA in milk samples.

State-of-the-art applications of cyclodextrins as functional monomers in molecular imprinting techniques: a review.

As a versatile tool in separation science, cyclodextrins and their derivatives, known as emerging functional monomers, have been used extensively in molecular imprinting techniques. The attributes of cyclodextrins and their derivatives are widely known to form host-guest inclusion complex processes between the polymer and template. The exploitation of the imprinting technique could produce a product of molecularly imprinted polymers, which are very robust with long-term stability, reliability, cost-efficiency, and selectivity. Hence, molecularly imprinted polymers have gained popularity in chemical separation and analysis. Molecularly imprinted polymers containing either cyclodextrin or its derivatives demonstrate superior binding effects for a target molecule. As noted in the previous studies, the functional monomers of cyclodextrins and their derivatives have been used in molecular imprinting for selective separation with a wide range of chemical compounds, including steroidals, amino acids, polysaccharides, drugs, plant hormones, proteins, pesticides, and plastic additives. Therefore, the main goal of this review is to illustrate the exotic applications of imprinting techniques employing cyclodextrins and their derivatives as single or binary functional monomers in synthesizing molecularly imprinted polymers in areas of separation science by reviewing some of the latest studies reported in the literature.

Molecularly imprinted polymers as the extracted sorbents of clenbuterol ahead of liquid chromatographic determination.

A pre-treatment methodology for clenbuterol hydrochloride (CLEN) isolation and enrichment in a complex matrix environment was developed through exploiting molecularly imprinted polymers (MIPs). CLEN-imprinted polymers were synthesized by the combined use of ally-β-cyclodextrin (ally-β-CD) and methacrylic acid (MAA), allyl-β-CD and acrylonitrile (AN), and allyl-β-CD and methyl methacrylate (MMA) as the binary functional monomers. MAA-linked allyl-β-CD MIPs (M-MAA) were characterized by Fourier transform-infrared (FT-IR) spectroscopy and a scanning electron microscope (SEM). Based upon the results, M-MAA polymers generally proved to be an excellent selective extraction compared to its references: AN-linked allyl-β-CD MIPs (M-AN) and MMA-linked allyl-β-CD MIPs (M-MMA). M-MAA polymers were eventually chosen to run through a molecularly imprinted solid-phase extraction (MISPE) micro-column to enrich CLEN residues spiked in pig livers. A high recovery was achieved, ranging from 91.03% to 96.76% with relative standard deviation (RSD) ≤4.45%.

Preparation and Application of Magnetic Bisphenol A Imprinted Polymers with Binary Functional Monomers

A kind of magnetic molecularly imprinted polymers( mag-MIPs) was synthesized by heated polymerization technique using bisphenol A( BPA) as template,β-cyclodextrin( β-CD) and 4-vinylpyridine( 4-VP) as the binary functional monomers. The mag-MIPs were characterized by means of transmission electron microscopy( TEM),Fourier transform infrared spectroscopy( FTIR) and vibrating sample magnetometer( VSM). Adsorption experiments indicated that the mag-MIPs prepared with β-CD and 4-VP exhibited high selectivity toward BPA. The performance of the mag-MIPs used as magnetic solid-phase extraction( M-SPE) sorbent was evaluated,and the results showed that it could selectively extract BPA from water samples. The imprinted magnetic solid-phase extraction method has been applied for preconcentration and purification of BPA from water samples with the recoveries range of 90. 51%—98. 21%.

Synthesis and properties of magnetic molecularly imprinted polymers based on multiwalled carbon nanotubes for magnetic extraction of bisphenol A from water.

Novel magnetic molecularly imprinted polymers based on multiwalled carbon nanotubes (MWNTs@MMIPs) with specific selectivity toward bisphenol A were synthesized using bisphenol A as the template molecule, methacrylic acid, and β-cyclodextrin as binary functional monomers and ethylene glycol dimethacrylate as the cross-linker. The MWNTs@MMIPs were characterized by Fourier transform infrared, vibrating sample magnetometer, and transmission electron microscopy. Batch mode adsorption experiment was carried out to investigate the specific adsorption equilibrium and kinetics of the MWNTs@MMIPs. The MWNTs@MMIPs exhibited good affinity with a maximum adsorption capacity of 49.26 μmol g(-1) and excellent selectivity toward bisphenol A. Combined with high-performance liquid chromatography analysis, the MWNTs@MMIPs were employed to extract bisphenol A in tap water, rain water, and lake water successfully with the recoveries of 89.8-95.4, 89.9-93.4, and 87.3-94.1%, respectively.

Molecularly imprinted polymers of allyl-β-cyclodextrin and methacrylic acid for the solid-phase extraction of phthalate

β-Cyclodextrin was derived by allylic bromine (allyl-β-CD). A new kind of molecularly imprinted polymers (MIPs) with selective adsorption for phthalate were prepared using allyl-β-CD and methacrylic acid (MAA) as the binary functional monomers. The allyl-β-CD-MIPs were characterized by scanning electron micrograph (SEM) and Fourier transform-infrared spectroscopy (FT-IR). In this work, dipentyl phthalate (DPP) was selected as template; the interaction of DPP with MAA, acrylamide (AM) and methyl methacrylate (MMA) were compared by UV spectroscopic techniques. Facts of adsorption solvent, adsorption kinetics and adsorption selectivity were studied in the static adsorption methods. The scatchard plot suggested that the template-polymer system has two site of adsorption behavior with adsorption capacities of 1.170 mg/g and 6.244 mg/g, respectively. The (allyl-β-CD)-MIPs were used as selective sorbents for the solid-phase extraction (SPE) in the dynamic methods. The results indicated that (allyl-β-CD)-MIPs have specific recognition selectivity and excellent adsorption affinity for DPP. Finally, the (allyl-β-CD)-MIPs were used for molecularly imprinted solid-phase extraction (MISPE) to analyze the phthalates in cow milk.

Preparation of l-phenylalanine imprinted polymer based on monodisperse hybrid silica microsphere and its application on chiral separation of phenylalanine racemates as HPLC stationary phase

In this paper, a l-phenylalanine (l-Phe) imprinted polymer (MIP) based on monodisperse hybrid silica microspheres (MH-SiO2) with CHCH2 groups was synthesized by surface imprinting technique. The MH-SiO2 was synthesized by a sol–gel process in aqueous media using tetraethylorthosilicate (TEOS) and 3-methylacryloxypropyl trimethoxysilane (MATES) as the precursors. The morphologies of MH-SiO2 and MIP were characterized with scanning electron microscope (SEM) and the imprinted shell thickness on the surface of MH-SiO2 was calculated as 0.5μm. Compared with the imprinted polymer prepared only by β-cyclodextrin (β-CD) or methacrylic acid (MAA) as functional monomer, the imprinted polymer prepared with both β-CD and MAA as binary functional monomers hold the highest adsorption capacity. Under the optimum chromatographic conditions, a complete baseline separation of phenylalanine racemates was observed only using the column packed with the imprinted polymer prepared with both β-CD and MAA as binary functional monomers. And the separation factor and resolution of the imprinted polymer towards phenylalanine racemates were calculated as 1.41 and 1.46, respectively, which is higher than that of other imprinted polymers.

A novel ionic liquid monolithic column and its separation properties in capillary electrochromatography

A novel ionic liquid (IL) monolithic capillary column was successfully prepared by thermal free radical copolymerization of IL (1-vinyl-3-octylimidazolium chloride, ViOcIm +Cl −) together with lauryl methacrylate (LMA) as the binary functional monomers and ethylene dimethacrylate (EDMA) as the cross-linker in binary porogen. The proportion of monomers, porogens and cross-linker in the polymerization mixture was optimized in detail. The resulting IL-monolithic column could not only generate a stable reversed electroosmotic flow (EOF) in a wide pH range (2.0–12.0), but also effectively eliminate the wall adsorption of the basic analytes. The obtained IL-monolithic columns were examined by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR). These results indicated that the IL-monolithic capillary column possessed good pore properties, mechanical stability and permeability. The column performance was also evaluated by separating different kinds of compounds, such as alkylbenzenes, thiourea and its analogues, and amino acids. The lowest plate height of ∼6.8 μm was obtained, which corresponded to column efficiency (theoretical plates, N) of ∼147,000 plates m −1 for thiourea. ILs, as a new type of functional monomer, present a promising option in the fabrication of the organic polymer-based monolithic columns in CEC.

Novel molecularly imprinted polymers based on multi-walled carbon nanotubes with binary functional monomer for the solid-phase extraction of erythromycin from chicken muscle

A new surface imprinting technique was reported to synthesize multi-walled carbon nanotubes-molecularly imprinted polymers (MWNTs-MIPs) using erythromycin as the template, acryloyl- β-cyclodextrin (acryloyl- β-CD) and methacrylic acid (MAA) as the binary functional monomers. The MWNTs-MIPs were characterized by transmission electron microscopy (TEM), scanning electron micrograph (SEM) and Fourier transform-infrared spectroscopy (FT-IR). Adsorption experiments indicated the MWNTs-MIPs prepared with acryloyl- β-CD and MAA have high selective for erythromycin. The feasibility of the MWNTs-MIPs as solid-phase extraction (SPE) sorbent was evaluated, and the results showed that it can selectively extract erythromycin from chicken muscle samples with the recoveries ranging from 85.3% to 95.8%. The molecularly imprinted solid-phase extraction (MISPE) method could be applied for preconcentration and purification of erythromycin from chicken muscle samples.

Preparation of magnetic indole-3-acetic acid imprinted polymer beads with 4-vinylpyridine and β-cyclodextrin as binary monomer via microwave heating initiated polymerization and their application to trace analysis of auxins in plant tissues

Auxin is a crucial phytohormone for precise control of growth and development of plants. Due to its low concentration in plant tissues which are rich in interfering substances, the accurate determination of auxins remains a challenge. In this paper, a new strategy for isolation and enrichment of auxins from plant tissues was obtained by the magnetic molecularly imprinted polymer (mag-MIP) beads, which were prepared by microwave heating initiated suspension polymerization using indole-3-acetic acid (IAA) as template. In order to obtain higher selective recognition cavities, an enhanced imprinting method based on binary functional monomers, 4-vinylpyridine (4-VP) and β-cyclodextrin (β-CD), was adopted for IAA imprinting. The morphological and magnetic characteristics of the mag-MIP beads were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy and vibrating sample magnetometry. A majority of resultant beads were within the size range of 80–150 μm. Porous surface morphology and good magnetic property were observed. Furthermore, the mag-MIP beads fabricated with 4-VP and β-CD as binary functional monomers exhibited improved recognition ability to IAA, as compared with the mag-MIP beads prepared with the individual monomer separately. Competitive rebinding experiment results revealed that the mag-MIP beads exhibited a higher specific recognition for the template than the non-imprinted polymer (mag-NIP) beads. An extraction method by mag-MIP beads coupled with high performance liquid chromatography (HPLC) was developed for determination of IAA and indole-3-butyric acid (IBA) in plant tissues. Linear ranges for IAA and IBA were in the range of 7.00–100.0 μg L −1 and 10.0–100.0 μg L −1, and the detection limits were 3.9 and 7.4 μg L −1, respectively. The analytical performance was also estimated by seedlings or immature embryos samples from three different plant tissues, pea, rice and wheat. Recoveries were in the range of 70.1–93.5%. The results show that the present imprinting method is a promising approach for preparation of selective adsorbents for sample preparation of auxin analysis in plant tissues.