Co-reporter:Yun-Kai Lv, Jing Zhang, Meng-Zhe Li, Shao-Dan Zhou, Xing-Hui Ren and Jing Wang
Analytical Methods 2016 vol. 8(Issue 19) pp:3982-3989
Publication Date(Web):08 Apr 2016
DOI:10.1039/C6AY00417B
A novel restricted-access media molecularly imprinted magnetic microsphere (RAM-MIMM) was prepared by an initiator-transfer agent-terminator (iniferter) method. The iniferter was synthesized by coating magnetic nanoparticles with silica-gel, modifying them with an amino-group and reacting with 4-(chloromethyl)benzoyl chloride and sodium diethyldithiocarbamate. The molecularly imprinted magnetic microsphere (MIMM) was prepared using florfenicol (FF) as the template, itaconic acid (ITA) as the functional monomer, ethylene dimethacrylate (EDMA) as the cross-linker, and the iniferter as the surface initiator in anhydrous ethanol solvent. The hydrophilic external layer of the MIMM was formed by iniferter polymerization using glycidyl methacrylate (GMA) as monomer, followed by hydrolysis of the linear poly(GMA). The obtained RAM-MIMMs were characterized by TEM, TGA, FT-IR and adsorption experiments. The Fe3O4 magnetic microspheres were demonstrated to have average diameters around 230 nm and coating thicknesses in the range 20–30 nm. The RAM-MIMMs exhibited high selectivity (1.68) with respect to the imprinted cavities and a hydrophilic external surface with water compatibility and exclusion biomacromolecules. The RAM-MIMMs were used for magnetic dispersion extraction of FF from milk samples. Average recoveries were in the range 85.4–94.7% with a precision of 2.95–4.97%. The limits of detection and quantitation of the proposed method were in the ranges 4.40–18.31 μg kg−1 and 14.66–61.02 μg kg−1, respectively. The proposed method was successfully applied to fast clean-up and selective enrichment of florfenicol in milk.
Co-reporter:Yun-Kai Lv, Yan-Dong He, Xue Xiong, Jin-Zhi Wang, Hai-Yan Wang and Ya-Meng Han
New Journal of Chemistry 2015 vol. 39(Issue 3) pp:1792-1799
Publication Date(Web):17 Dec 2014
DOI:10.1039/C4NJ01882F
A novel restricted access media-molecularly imprinted magnetic microsphere (RAM-MIMM) was prepared through layer by layer modification. The magnetic nanoparticles were coated with silica gel, modified with the amino group, coated by BPA-imprinted sol–gel film and grafted with the epoxy silane coupling agent. The RAM-MIMMs were characterized by SEM, TEM, FT-IR and adsorption experiments. The RAM-MIMMs were prepared with the average diameters of around 300 nm and the coating thickness in the range of 10–15 nm, and exhibited high selectivity (2.54) of the imprinted cavities and hydrophilicity of the external surface with water compatibility and exclusion biomacromolecules. The RAM-MIMMs were used for magnetic dispersion microextraction of BPA from milk samples. The average recoveries were obtained in the range of 85.2–98.6% with a precision of 2.2–4.6%. The limits of detection and quantitation of the proposed method were in the range of 4.70–10.51 μg kg−1 and 15.65–35.02 μg kg−1, respectively.
Co-reporter:Yun-Kai Lv, Zhi-Yong Guo, Jin-Zhi Wang, Meng-Meng Guo, Lin-Kang Yu and Hui Fang
Analytical Methods 2015 vol. 7(Issue 4) pp:1563-1571
Publication Date(Web):23 Dec 2014
DOI:10.1039/C4AY02787F
A novel restricted access material–hybrid monolithic column (RAM–HMC) was prepared by the sol–gel method in a stainless-steel column and an in situ modification method in the through-hole of the HMC. The hydrophobic HMC was prepared by the acid-catalytic reaction of methyltrimethoxysilane and tetraethoxysilane. The hydrophilic structures were formed on the through-hole surface of the HMC by grafting 3-(2,3-epoxypropoxy) propyltrimethoxysilane. The synthetic conditions were optimized for obtaining the uniform microchannel and the stable skeleton structure. The chemical group, morphology, dynamic adsorption capacity, swelling, and hydrophilic and hydrophobic characteristics of the monolithic column were characterized by the IR, SEM, dynamic binding, solvent adsorption, chromatographic analysis of serum proteins and benzene series, respectively. When the RAM–HMC was used as a precolumn for the on-line extraction of sulfonamide residues from the honey samples, an enrichment factor of 16.9 and a better sample clean-up effect were obtained under the optimized conditions. The average recoveries of three sulfonamide antibiotics from honey spiked at 0.05, 0.1 and 0.2 mg kg−1 were in the range of 73.50–105.80% with a precision of 2.25–5.32%. The limits of detection and quantitation of the proposed method ranged from 6.9–14.6 μg kg−1 and 23.0–48.2 μg kg−1, respectively. The proposed method was successfully applied to the on-line extraction and determination of sulfonamide antibiotics in the honey sample.
Co-reporter:Yun-Kai Lv, Wei Zhang, Meng-Meng Guo, Fang-Fang Zhao and Xiao-Xue Du
Analytical Methods 2015 vol. 7(Issue 2) pp:560-565
Publication Date(Web):18 Aug 2014
DOI:10.1039/C4AY01705F
A home-made centrifugal microextraction tube (CMET) was developed and applied to cloud point extraction coupled with microwave-assisted back extraction and gas chromatographic separation of six phthalate esters (PAEs) from mineral water. All phthalate esters were entrapped in the micelles of the non-ionic surfactant Triton X-114 and removed from the bulk phase by centrifugation. The obtained surfactant-rich phase was treated with water-immiscible solvents, and the target analytes were back extracted by short-term microwave application and determined by GC-FID directly. The whole process was finished in the CMET. The proposed method demonstrated good performance concerning linearity (R2 = 0.9977-0.9998), precision (2.3–5.7%), the limits of detection and quantitation (LOD, 11.5-19.3 μg L−1; LOQ, 37.0-63.3 μg L−1), spiked recoveries (89.1–96.3%) and enrichment factor (71-85). The proposed method was successfully applied for the determination of trace amount of phthalate esters in mineral water. DBP and BBP were found in actual mineral water samples.
Co-reporter:Yun-Kai Lv, Jing-Qi Zhang, Yan-Dong He, Jing Zhang and Han-Wen Sun
New Journal of Chemistry 2014 vol. 38(Issue 2) pp:802-808
Publication Date(Web):02 Dec 2013
DOI:10.1039/C3NJ00962A
Molecularly imprinted organic–inorganic hybrid composite materials (MIP-HCMs) with controlled swelling and adsorption properties were prepared through copolymerization and the sol–gel process by using doxycycline (DC) as the template molecule, methacrylic acid (MAA) as a functional monomer, methacryloxypropyltrimethoxysilane (KH-570) as a coupling agent and TEOS as an inorganic precursor. By means of changing polymerization conditions as well as the copolymerization ratio of the inorganic precursor and the organic functional monomer, the properties of sorbents can be adjusted for different needs. So the effect of preparation conditions on the structure of the material was studied. The polymer group, thermal stability, adsorption and selectivity characteristics, and the volume swelling degree of the MIP-HCMs were characterized by FTIR, TGA, and dynamic adsorption and swelling experiments, respectively. It was observed that the MIP-HCMs exhibited the highest selectivity (4.9), maximum adsorption capacity (58.2 mg g−1) and good thermal stability. The obtained MIP-HCM was used as an adsorbent for solid-phase extraction of tetracyclines from the milk and honey samples. The average recoveries of three tetracycline antibiotics (DC, tetracycline and chlortetracycline) were obtained in the range of 74.7–115.5% with the precision of 2.1–4.9%. The limits of detection and quantitation of the proposed method were in the range of 4.9–15.3 μg kg−1 and 16.6–51.0 μg kg−1 for the milk samples, and 8.3–15.1 μg kg−1 and 18.3–50.2 μg kg−1 for the honey samples, respectively.
Co-reporter:Yun-Kai Lv;Chen-Xi Zhao;Pan Li;Yan-Dong He;Zhong-Rui Yang ;Han-Wen Sun
Journal of Separation Science 2013 Volume 36( Issue 16) pp:2656-2663
Publication Date(Web):
DOI:10.1002/jssc.201300429
A magnetic dispersion extraction method was developed based on a molecularly imprinted magnetic microsphere (MIMM) for the selective clean-up and enrichment of tetracycline antibiotics from milk samples. The MIMMs were prepared by inverse-emulsion suspension polymerization, using doxycycline, trimethylolpropane trimethacrylate, acrylamide, methacrylic acid, and surface-modified Fe3O4 as a template molecule, crosslinker, functional monomer, and magnetic component, respectively. Synthesis and extraction conditions were optimized for obtaining excellent affinity and high selectivity. The magnetism, covering amount, and selectivity of the magnetic microspheres were characterized by a vibrating sample magnetometer, thermogravimetric analysis, and a competitive recognition experiment. The MIMMs were applied to separate tetracycline antibiotics from milk samples by magnetic dispersion extraction, and an enrichment factor of 9.28 and a good sample clean-up were obtained. The average recoveries of four tetracycline antibiotics were obtained in the range of 74.5–93.8% with a precision of 1.2–5.2%. The LODs and LOQs of the proposed method were in the range of 7.4–19.4 and 24.7–64.7 μg/kg, respectively. The results indicated that magnetic dispersion extraction using MIMMs is a powerful tool for food-sample pretreatment with high selectivity and a simplified procedure.
Co-reporter:Yun-Kai Lv, Lei Yang, Xiao-Hui Liu, Zhi-Yong Guo and Han-Wen Sun
Analytical Methods 2013 vol. 5(Issue 7) pp:1848-1855
Publication Date(Web):24 Jan 2013
DOI:10.1039/C3AY26431A
A novel molecularly imprinted organic–inorganic hybrid composite monolithic column (MIP-HCMC) was prepared in a stainless-steel chromatographic column for the determination of fluoroquinolone residues in milk by on-line solid-phase extraction coupled with HPLC. The MIP-HCMC was prepared using enrofloxacin as the template, methacrylic acid and 2-hydroxyethyl methacrylate as functional monomers, tetraethoxysilane as inorganic precursor and methacryloxypropyltrimethoxysilane as coupling agent, toluene and polyethylene glycol as porogenic solvents, and ethylene glycol dimethacrylate as the cross-linking agent. The synthetic conditions were optimized. The chemical group, morphology, thermal stability, dynamic adsorption characteristic and swelling of the monolithic column were characterized by IR, SEM, TG, dynamic binding tests and swelling tests, respectively. An enrichment factor (EF) of 18.5 along with a good sample clean-up effect was obtained under the optimized conditions when the method was applied to milk sample analysis only after centrifugation. The average recoveries of four fluoroquinolones from milk spiked at 0.05, 0.1 and 0.25 mg kg−1 were in the range of 89.1–99.2% with the precision of 3.55–4.32%. The limits of detection and quantification of the proposed method were 1.69 and 5.63 μg kg−1 for ofloxacin, 1.63 and 5.43 μg kg−1 for lomefloxacin, 3.74 and 12.5 μg kg−1 for ciprofloxacin, 1.37 and 4.56 μg kg−1 for enrofloxacin, respectively. The proposed method was successfully applied to on-line extraction and determination of fluoroquinolone antibiotics in milk.
Co-reporter:Yun-Kai Lv, Li-Min Wang, Lei Yang, Chen-Xi Zhao, Han-Wen Sun
Journal of Chromatography A 2012 Volume 1227() pp:48-53
Publication Date(Web):2 March 2012
DOI:10.1016/j.chroma.2011.12.108
A novel molecularly imprinted organic–inorganic hybrid composite material (MIP-HCM) was developed based on molecular imprinting technique in combination with hybrid composite synthesis and sol–gel technology for selective solid-phase extraction (SPE) of tetracyclines residues in milk. The MIP-HCM was prepared using oxytetracycline as the template, methacrylic acid as organic functional monomer, tetraethoxysilane as inorganic precursor and methacryloxypropyltrimethoxysilane as the coupling agent. Synthesis conditions are optimized by changing some factors to obtain sorbent with the controllable adsorption capacity, selectivity, hardness and toughness. Binding study demonstrated that the imprinted hybrid composites showed excellent affinity and high selectivity to oxytetracycline. An enrichment factor of 18.8 along with a good sample clean-up was obtained under the optimized SPE conditions. The average recoveries of three tetracyclines antibiotics spiked milk at 0.1, 0.2 and 0.5 mg kg−1 were in the range of 80.9–104.3% with the precision of 1.5–5.0%. The limits of detection and quantitation of the proposed method were in a range of 4.8–12.7 μg kg−1 and 16.0–42.3 μg kg−1, respectively.Highlights► A molecularly imprinted hybrid composite material (MIP-HCM) was synthesized. ► Synthesis conditions are optimized by changing some factors, such as components. ► The structural characteristics and adsorption properties of the MIP-HCM were investigated. ► Three tetracycline antibiotics residues in milk were separated and detected by MISPE-HPLC with better clean up and enrichment.
Co-reporter:Yun-Kai Lv;Li-Min Wang;Shuai-Lei Yan;Xiao-Hu Wang ;Han-Wen Sun
Journal of Applied Polymer Science 2012 Volume 126( Issue 5) pp:1631-1636
Publication Date(Web):
DOI:10.1002/app.36795
Abstract
A novel molecular imprinting method for the preparation of molecularly imprinted poly(methacrylic acid)/silica hybrid composite materials (MIP-HCMs) for the selective recognition of lincomycin (LIN) in aqueous media by prepolymerization and free-radical copolymerization was investigated. In this study, methacrylic acid was selected as the functional monomer, methacryloxypropyltrimethoxysilane was used as the crosslinker, and tetraethoxysilane was used as the inorganic precursor. MIP-HCM was characterized by FTIR spectroscopy, the Brunauer–Emmett–Teller method, and TGA. The selectivity of the sorbent was investigated by a batch competitive binding experiment with an aqueous LIN and clindamycin (CLI) mixture. The selectivity coefficient for LIN in the presence of CLI was 6.27, whereas the relative selectivity coefficient between LIN and CLI was 5.83. The absorption capability of MIP-HCM and the selectivity coefficient were much higher than those of the nonimprinted blank polymer. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2012
Co-reporter:Yun-Kai Lv, Yong Ma, Xiao-Bo Zhao, Cui-Ling Jia, Han-Wen Sun
Talanta 2012 Volume 89() pp:270-275
Publication Date(Web):30 January 2012
DOI:10.1016/j.talanta.2011.12.026
A high-density imprinted polymeric membrane was immobilized on a porous silica-gel support by polymerization of methacrylic acid with vinyl-silanized silica gel for the selective solid-phase extraction (SPE) of norfloxacin (NOR) in fish samples. The imprinted membranes showed high adsorption capacity (423.2 μmol g−1), significant selectivity (k = 14.64, k′ = 9.61) and good site accessibility (2 h) for NOR. The conditions of SPE were investigated, and water (pH = 6), methanol:water (1:1, v/v) and methanol–acetic acid–trifluoroacetic acid (90:9:1, v/v) were selected as the sample solvent, the washing solution and the eluting solution, respectively. Under the optimal SPE condition, three fluoroquinolone residues in fish were separated and detected by an off-line MIP–SPE–HPLC with better clean up and enrichment. The recoveries of norfloxacin, ofloxacin and ciprofloxacin were 89.3–94.8%, 69.3–102.8% and 85–90.5%, respectively, with relative standard deviations lower than 6.5%. The limits of detection (LOD) of the proposed method (S/N = 3) were in a range of 2.65–3.65 μg kg−1, and the limits of quantification (LOQ, S/N = 10) were in a range of 8.82–12.16 μg kg−1.Highlights► A norfloxacin imprinted polymeric membrane was immobilized on a porous silica-gel support. ► The structural characteristics and adsorption properties of the MIP-Silica were investigated. ► The MISPE procedure was optimized to separate and detect three fluoroquinolone residues in fish.
Co-reporter:Yun-Kai Lv, Yue-Na Sun, Li-Min Wang, Cui-Ling Jia and Han-Wen Sun
Analytical Methods 2011 vol. 3(Issue 11) pp:2557-2561
Publication Date(Web):30 Sep 2011
DOI:10.1039/C1AY05426K
A simple, rapid, sensitive, and low cost method of ultrasonic extraction (USE) and capillary electrophoresis (CE) for the determination of melamine in milk is developed. The most widely used extraction methods of melamine (SPE and LLE) were compared with ultrasonic-assisted extraction by evaluating simplicity, cost and sample clean-up effect, and the conditions of CE were optimized. The melamine was extracted by acetonitrile under the action of ultrasonic energy. After centrifuging, diluting and filtering, the extract was analyzed by CE directly. The determination used 20 mM NaH2PO4 as running buffer (pH 2.6), UV detection at 208 nm, and an applied voltage of 18 kV. The proposed method demonstrated good performance concerning linearity (R2 = 0.9989), precision (2.6–4.8%), limit of detection and quantification (LOD, 0.163 mg kg−1; LOQ, 0.542 mg kg−1) and accuracy (85.1–98.3%). The proposed method is rapid, convenient and low-cost for the determination of melamine in milk products.
Co-reporter:
Analytical Methods (2009-Present) 2013 - vol. 5(Issue 7) pp:
Publication Date(Web):
DOI:10.1039/C3AY26431A
A novel molecularly imprinted organic–inorganic hybrid composite monolithic column (MIP-HCMC) was prepared in a stainless-steel chromatographic column for the determination of fluoroquinolone residues in milk by on-line solid-phase extraction coupled with HPLC. The MIP-HCMC was prepared using enrofloxacin as the template, methacrylic acid and 2-hydroxyethyl methacrylate as functional monomers, tetraethoxysilane as inorganic precursor and methacryloxypropyltrimethoxysilane as coupling agent, toluene and polyethylene glycol as porogenic solvents, and ethylene glycol dimethacrylate as the cross-linking agent. The synthetic conditions were optimized. The chemical group, morphology, thermal stability, dynamic adsorption characteristic and swelling of the monolithic column were characterized by IR, SEM, TG, dynamic binding tests and swelling tests, respectively. An enrichment factor (EF) of 18.5 along with a good sample clean-up effect was obtained under the optimized conditions when the method was applied to milk sample analysis only after centrifugation. The average recoveries of four fluoroquinolones from milk spiked at 0.05, 0.1 and 0.25 mg kg−1 were in the range of 89.1–99.2% with the precision of 3.55–4.32%. The limits of detection and quantification of the proposed method were 1.69 and 5.63 μg kg−1 for ofloxacin, 1.63 and 5.43 μg kg−1 for lomefloxacin, 3.74 and 12.5 μg kg−1 for ciprofloxacin, 1.37 and 4.56 μg kg−1 for enrofloxacin, respectively. The proposed method was successfully applied to on-line extraction and determination of fluoroquinolone antibiotics in milk.
Co-reporter:Yun-Kai Lv, Yue-Na Sun, Li-Min Wang, Cui-Ling Jia and Han-Wen Sun
Analytical Methods (2009-Present) 2011 - vol. 3(Issue 11) pp:NaN2561-2561
Publication Date(Web):2011/09/30
DOI:10.1039/C1AY05426K
A simple, rapid, sensitive, and low cost method of ultrasonic extraction (USE) and capillary electrophoresis (CE) for the determination of melamine in milk is developed. The most widely used extraction methods of melamine (SPE and LLE) were compared with ultrasonic-assisted extraction by evaluating simplicity, cost and sample clean-up effect, and the conditions of CE were optimized. The melamine was extracted by acetonitrile under the action of ultrasonic energy. After centrifuging, diluting and filtering, the extract was analyzed by CE directly. The determination used 20 mM NaH2PO4 as running buffer (pH 2.6), UV detection at 208 nm, and an applied voltage of 18 kV. The proposed method demonstrated good performance concerning linearity (R2 = 0.9989), precision (2.6–4.8%), limit of detection and quantification (LOD, 0.163 mg kg−1; LOQ, 0.542 mg kg−1) and accuracy (85.1–98.3%). The proposed method is rapid, convenient and low-cost for the determination of melamine in milk products.
