磁性双酚A分子印迹材料的制备及性能研究

采用沉淀法制备了Fe_3O_4磁性微球,以硅烷化试剂对其表面改性后作为载体,以双酚A为模板分子,甲基丙烯酸为功能单体,N,N′-亚甲基双丙烯酰胺为交联剂,采用乳液聚合法制备了对BPA有特异吸附性能的磁性分子印迹材料(MMIPs)。此材料具有较强的磁性和对双酚A的吸附性,可以在外加磁场的条件下方便实现水中双酚A的富集分离。溶液中双酚A的质量浓度为60mg·L~(-1)时,制备的磁性MIPs材料对双酚A饱和吸附量为22.06mg·g~(-1),60min达到吸附平衡。     

基于固绿褪色反应的分光光度法测定双酚A的含量

在硫酸介质中,Fenton反应产生的羟基自由基使固绿褪色,双酚A对羟基自由基氧化固绿的反应具有抑制作用,据此提出了测定双酚A含量的固绿褪色-分光光度法。优化的试验条件如下:1 0.005mol·L~(-1)硫酸溶液的用量为200μL;2 0.005mol·L~(-1)硫酸亚铁溶液的用量为75μL;380mg·L~(-1)固绿溶液的用量为300μL;420mmol·L~(-1)过氧化氢溶液的用量为60μL;5反应时间为10min;6反应温度为50℃。双酚A的质量浓度在1.6×10-5~2.0×10-4g·L~(-1)范围内与其吸光度呈线性关系,检出限(3σ)为6.3×10-6g·L~(-1)。加标回收率在94.2%~104%之间,测定值的相对标准偏差(n=5)在2.9%~3.2%之间。     

聚氨基苯酚分子印迹电化学传感器测定双酚A

该工作通过电化学方法在多壁碳纳米管修饰的玻碳电极表面得到聚邻氨基苯酚分子印迹聚合物膜,制备了可以选择性识别双酚A的分子印迹电化学传感器。通过扫描电镜、循环伏安法以及差分脉冲法对传感器的表面形貌和电化学性能进行了表征,并对传感器的检测条件进行了优化。采用K_3[Fe(CN)_6]作为电化学探针,在选定的实验条件下,K_3[Fe(CN)_6]在印迹电极上的峰电流变化值与双酚A的浓度在1×10~(-10)-4×10~(-8) mol·L~(-1)呈良好线性,本方法测定双酚A的检测限为4×1 0 ~(-11) mol·L~(-1),将该传感器用于实际水样中双酚A的测定,结果令人满意。     

高效液相色谱法同时测定塑料食品接触材料中双酚S、双酚A和4,4′-二氯二苯砜的迁移量

样品经水、4%(体积分数)乙酸溶液、20%(体积分数)乙醇溶液、50%(体积分数)乙醇溶液等4种食品模拟物浸泡后,浸泡液用0.45μm滤膜过滤。采用Agilent Eclipse XDB-C18色谱柱(250mm×4.6mm,5μm)分离待测物,以乙腈-水混合液为流动相进行梯度洗脱,采用二极管阵列检测器分别在259,228,247nm处测定双酚S、双酚A和4,4′-二氯二苯砜。双酚S、双酚A和4,4′-二氯二苯砜的线性范围均为0.02~5.0 mg·L~(-1),检出限(3S/N)分别为0.01,0.02,0.01mg·L~(-1)。加标回收率在89.6%~103%之间,测定值的相对标准偏差(n=6)在0.84%~3.2%之间。     

基于分子印迹识别的化学发光微流控传感器芯片测定双嘧达莫

试验中,以双嘧达莫为模板分子,α-甲基丙烯酸为功能单体,乙二醇二甲基丙烯酸酯为交联剂,氯仿为溶剂,合成了双嘧达莫分子印迹聚合物。将此聚合物填充在长8 mm,宽1 mm,深0.5 mm的微流控芯片检测池中作为分子识别物质,设计了一种新型的化学发光微流控传感器芯片测定双嘧达莫。双嘧达莫被此聚合物在线吸附并识别,被吸附的双嘧达莫与鲁米诺和铁氰化钾混合溶液反应并导致其化学发光强度增大。该传感器对双嘧达莫响应范围为1.0～20μg·L~(-1),检出限(3σ)为0.5μg·L~(-1),对10μg·L~(-1)双嘧达莫连续平行测定7次,其相对标准偏差为4.6%。     

表面印迹聚合物萃取/气相色谱质谱联用检测双酚A

以双酚A(BPA)为模板分子,甲基丙烯酸为单体,乙二醇二甲基丙烯酸酯作为交联剂,在硅胶表面合成双酚A分子印迹聚合物。通过红外光谱、比表面积测定等对表面印迹聚合物进行分析和表征;采用静态吸附法和动态吸附法对其吸附性能进行考察。红外光谱表明硅胶表面生成了对模板分子具有识别功能的官能团;热重分析证明该印迹聚合物具有良好的热稳定性;静态吸附实验说明表面印迹聚合物比非印迹聚合物具有良好的吸附性能,该印迹聚合物对双酚A最大吸附容量Q max为1.501 mg/g,吸附速率常数k为0.01586g/(mg·min)。用表面印迹聚合物萃取(MISPE)和气相色谱质谱(GC-MS)联用检测了BPA样品,BPA的回收率接近90%,并将该双酚A表面印迹聚合物用于牛奶样品中的BPA测试,结果表明该印迹聚合物具有较好的吸附选择性。     

室温离子液体负载环糊精磁性纳米材料固相萃取分离与富集饮料中双酚A及其含量的高效液相色谱法测定

先由羟丙基-β环糊精与环氧氯丙烷在碱性溶液中反应制得羟丙基-β-环糊精聚合物,再由所制得的羟丙基-β-环糊精聚合物与氯乙酸钠反应制得羧甲基-羟丙基-β-环糊精聚合物,并将此聚合物与硫酸亚铁及三氯化铁共溶于水中,并在90℃的氨性介质中反应得到Fe_3O_4/羟丙基-β-环糊精聚合物纳米材料。最后将上述纳米材料在[C_4min]PF_6中搅拌浸泡,并经抽滤和在90℃下干燥获得室温离子液体负载环糊精磁性纳米材料(简称磁性纳米材料)。应用此磁性纳米材料作为吸附剂分离、富集饮料中可能存在的双酚A,具体步骤如下:取样品50.0mL,调节其酸度至pH 7.0,加入磁性纳米材料0.1g,振荡提取5.0min,弃去上层溶液,用甲醇2.0mL将双酚A从磁性纳米材料上超声洗脱10.0min,收集洗脱液经0.22μm滤膜过滤,所得滤液供高效液相色谱法分析。以Agilent EC-C_(18)色谱柱为固定相,以不同比例的乙腈(A)和水(B)的混合液作为流动相进行梯度洗脱,采用荧光检测器检测。测得双酚A的线性范围在2.40～800μg·L~(-1)之间,检出限(3S/N)为0.40μg·L~(-1),富集倍数为25。以空白果汁样品为基体,用标准加入法进行回收试验,测得回收率在95.0%～98.0%之间,测定值的相对标准偏差(n=5)在2.3%～5.1%之间。     

新型磁性分子印迹聚合物快速萃取-高效液相色谱法测定牛血清白蛋白

以牛血清白蛋白(BSA)为模板分子,多巴胺为功能单体,磁性四氧化三铁-石墨烯-多壁碳纳米管(Fe_3O_4-G/MWNT)为载体,制备了一种新型磁性分子印迹聚合物材料(Fe_3O_4-G/MWNT@MIP),用于萃取牛血清白蛋白。用10 mmol·L~(-1)的磷酸盐缓冲溶液(pH 6.0,含1.0mmol·L~(-1) NaCl)将血清样品稀释10倍,加入20.0mg的Fe_3O_4-G/MWNT@MIP,振摇平衡20min,弃去液体,用5.0 mL的10 mmol·L~(-1) NaCl溶液(pH 6.0)洗涤固体,再用2.0 mL的0.5mmol·L~(-1) NaCl溶液(pH 5.0)解吸20min,将洗脱液移至超滤管中,以12 000转·min~(-1)离心20min后,取超滤液进行高效液相色谱分析。结果表明:Fe_3O_4-G/MWNT@MIP对BSA具有良好的选择性,最大吸附容量达56.79mg·g~(-1),重复使用20次后,最大吸附容量仅降低了7%。方法成功于应用于小牛血清中牛血清白蛋白的测定,加标回收率在90.0%～120%之间,测定值的相对标准偏差(n=7)小于3.0%。     

磁性氧化石墨烯壬基酚分子印迹聚合物的制备及吸附性能研究

以磁性氧化石墨烯(Fe3O4@GO)为载体,2-乙烯基吡啶为功能单体,乙二醇二甲基丙烯酸酯为交联剂,利用表面聚合技术制备了对壬基酚(NP)有特异吸附性能的分子印迹聚合物。电子显微镜表征和静态吸附试验结果表明:分子印迹聚合物已修饰在Fe3O4@GO表面,且该聚合物对壬基酚有良好的吸附性能,其最大吸附量为27.99g·kg~(-1)。以该分子印迹聚合物为固相萃取材料,乙腈为上样溶剂、甲醇-乙酸(9+1)溶液为洗脱剂,采用高效液相色谱法对牛奶塑料包装袋中壬基酚进行富集和测定。NP质量浓度的线性范围为2.0~100μg·L~(-1),检出限(3S/N)为0.34μg·kg~(-1)。加标回收率在86.1%~95.2%之间,测定值的相对标准偏差(n=5)小于5.0%。     

分子印迹固相萃取-化学发光法测定贝母素甲

将制备的粒径为70~100μm贝母素甲分子印迹聚合物作为填料制作了分子印迹固相萃取(MIP-SPE)柱。将含有贝母素甲的样品溶液经过MIP-SPE后,在盐酸-高锰酸钾-甲醛的体系下,进行化学发光检测,建立了测定贝母属类样品中贝母素甲含量的分子印迹-化学发光法。贝母素甲的浓度在5.0×10~(-7)~5.0×10~(-5) mol·L~(-1)内与化学发光强度呈线性关系,检出限(3s)为2.0×10~(-7) mol·L~(-1)。加标回收率在97.2%~102%之间,测定值的相对标准偏差在1.7%~2.2%之间。     

Preparation of uniformly sized molecularly imprinted polymers for phenolic compounds and their application to the assay of bisphenol A in river water.

Uniformly sized molecularly imprinted polymers, which can recognize bisphenol A (BPA), have been prepared by a multi-step swelling and polymerization method using BPA or a structurally related analogue of BPA [p-t-octylphenol (OP) or p-t-butylphenol (BP)] as the template molecule, 4-vinylpyridine as the functional monomer, and ethylene glycol dimethacrylate as the cross-linker. The BP-imprinted polymer showed higher molecular recognition ability for BPA than the OP-imprinted polymer. The BPA- and BP-imprinted polymers were applied for the assay of a trace amount of BPA in river water using column-switching HPLC with fluorescence detection: A BPA-imprinted polymer was used for removal of BPA from the pretreatment eluent as the trap column, and a BP-imprinted polymer was used for selective pretreatment and enrichment of BPA in river water as the pretreatment column. The calibration graph, constructed from peak area data plotted versus BPA concentration, was linear with a correlation coefficient of >0.999 in the concentration ranges of 25-1000 ppt. The limit of quantitation was 25 ppt with a 5-ml injection. The column-switching HPLC system was successfully applied for the assay of BPA in river water.     

Selective Solid‐phase Extraction of Bisphenol A Using a Novel Stir Bar Based on Molecularly Imprinted Monolithic Material

In this paper, a novel monolithic stir bar based on molecularly imprinted polymer (MIP) was firstly developed by filling modified neodymium magnet (Nd₂Fe₁₄B) powders into a glass tube (60 × 4 mm), followed by the imprinted grafting with bisphenol A (BPA) as the template molecule by thermal polymerization. It has been successfully used for the stir bar sorptive extraction (SBSE) and its extraction performance illustrated that the MIP‐encapsulated stir bar had stronger affinity to the template molecule, compared with the stir bar based on the non‐imprinted molecularly polymer (NIP). Under the optimal extraction conditions, a simple method based on the coupling of MIP‐SBSE with high performance liquid chromatography (HPLC) was used for the selective determination of the model mixtures of BPA, 4‐phenylphenol (PP) and phenol (P) in bottled water. The recoveries of BPA, PP and P were in the range of 88.5‐96.1%, 78.2‐89.7%, 81.3‐89.5% at three spiked levels, respectively, demonstrating that higher extraction and the specific absorption occurred between the template molecule and the prepared MIP stir bar.     

Development of a molecularly imprinted polymer for selective extraction of bisphenol A in water samples

A cross‐linked methacrylate molecularly imprinted polymer (poly‐4‐vinylpyridine‐co‐trimethylolpropane‐trimethacrylate) selective for bisphenol A (BPA) was synthesized, using a fluorinated BPA derivative (4,4′‐(hexafluoroisopropylidene)‐diphenol) as a mimic template, and applied to the analysis of real‐world samples of process and potable waters. The molecularly imprinted polymer also showed a high affinity and selectivity for 17‐β‐estradiol and ethynylestradiol. A method to analyze BPA, 17‐β‐estradiol, and ethynylestradiol at ultratrace levels was thus developed from a screening procedure to monitor endocrine‐disrupting chemicals in water samples. The method consists of the BPA‐selective cleanup by molecularly imprinted SPE using cartridges packed with the polymer developed, its recovery by stir bar sorptive extraction after ad hoc derivatization to obtain the corresponding BPA‐acetate, and its analysis by GC‐time window‐SIM‐MS after online thermal desorption. The method showed good linearity in the working range (R²=0.9969), high repeatability (RSD% <10.1), recoveries always above 90%, and very low LOD (10 pg/L) and LOQ (1 ng/L) and can easily be extended to the determination of 17‐β‐estradiol and ethynylestradiol ultratraces. The method's effectiveness was evaluated by analyzing the real‐world water samples; it enabled preconcentration and detection of BPA at ultratrace levels.     

Direct injection analysis of bisphenol A in serum by combination of isotope imprinting with liquid chromatography-mass spectrometry

A restricted access media-molecularly imprinted polymer was prepared using bisphenol A (BPA)-d16 as a template molecule, and was successfully applied to direct injection analysis of BPA in serum combined with column-switching LC-MS.     

Selective molecularly imprinted polymer obtained from a combinatorial library for the extraction of bisphenol A

In the present work, an analytical methodology based on molecularly imprinted solid-phase extraction (MISPE) has been developed for the determination of bisphenol A (BPA) in environmental and food samples. In order to select the optimum material, a combinatorial library of molecularly imprinted polymers in small-scale (mini-MIPs) was prepared using BPA as template. Different monomers (methacrylic acid or 4-vinylpyridine), crosslinkers (ethylene glycol dimethacrylate or trimethylolpropane trimethacrylate) and porogens (methanol, acetonitrile or toluene) were used leading to 24 different polymerisation mixtures. After BPA removal, the ability of mini-MIPs to recognise BPA was evaluated by equilibrium rebinding-elution experiments. The copolymer of 4-vinylpyridine (4-VP) and trimethylolpropane trimethacrylate (TRIM) prepared in toluene showed the higher affinity for the template. Subsequently, a scaled-up version of the optimum polymer was prepared and used in the development of MISPE procedures for the extraction of BPA. The optimised MISPE protocols were successfully applied to the selective extraction of BPA from soils and aqueous canned peas samples.     

Bisphenol A analog-imprinted polymers prepared by an immobilized template on a modified silica microsphere matrix.

Bisphenol A (BPA)-recognizing imprinted polymers were synthesized using a template immobilized on silica where the template was grafted to aminopropyl silica. The silica-template conjugate was co-polymerized with a cross-linker (ethylene glycol dimethacrylate) and a functional monomer (4-vinylpyridine or methacrylic acid). The synthesized silica-polymer composites were treated with an aqueous NH4HF2 solution to dissolve the silica matrix. The 4-vinylpyridine-based imprinted polymer showed strong binding affinity to BPA and structurally related compounds having two hydroxyl groups at the 4,4'-position in the bisphenol structure.     

Bisphenol A-recognition polymers prepared by covalent molecular imprinting

A specific recognition material for bisphenol A (BPA) was prepared by using a covalent imprinting technique. A chloroform solution containing bisphenol A dimethacrylate as a template, ethylene glycol dimethacrylate as a cross-linking agent and 2,2′-azobis(isobutyronitrile) as an initiator was polymerized by UV initiation. When BPA was removed from the resulting polymer by hydrolysis of the ester bonds with aqueous sodium hydroxide, carboxylic acid residues were generated in the polymer. After the polymer was packed into a stainless steel column, retention factors of BPA and related compounds were measured. The imprinted polymer adsorbed BPA and structurally related compounds such as 4,4′-dihydroxybenzophenone, bis(4-hydroxyphenyl)sulfone and 4,4′-dihydroxybiphenyl. A typical association constant (K_a) was calculated to be 1.72×10⁵ M⁻¹ by Scatchard analysis. Interestingly, 17α- and 17β-estradiol were also bound to the imprinted polymer (K_a=1.68×10⁵ M⁻¹), indicating that the polymer could be used as artificial receptors for screening the compounds having estrogenic action.     

白藜芦醇分子印迹复合膜的制备及其选择性能

以反式白藜芦醇为模板分子,聚偏氟乙烯微孔滤膜为支撑膜,丙烯酰胺为功能单体,乙二醇二甲基丙烯酸脂(EDMA)为交联剂,采用热引发原位聚合方法制备了白藜芦醇分子印迹聚合物膜。研究了分子印迹膜对白藜芦醇及其结构类似物(2-萘酚、白藜芦醇甙和双酚A)的结合和透过性,并用扫描电镜对膜形貌进行了表征。结果表明,印迹复合膜对模板分子白藜芦醇具有良好的吸附选择性,印迹膜对白藜芦醇的吸附量远远大于其它结构类似物,其饱和吸附量达1.72μmol/g,为非印迹膜的3倍;尺寸效应和印迹效应是影响物质在印迹膜上的透过量的两个重要因素,尺寸比模板分子小的2-萘酚最先透过,而相对于尺寸接近或大于模板分子的双酚A或白藜芦醇甙,模板分子优先透过。而且,模板分子在印迹膜上的透过量大于非印迹膜。     

Highly selective stir bar coated with dummy molecularly imprinted polymers for trace analysis of bisphenol A in milk

A water compatible molecularly imprinted polymers (MIPs) coated stir bar for bisphenol A(BPA) was prepared with 3,3',5,5'-tetrabromobisphenol A as the dummy template molecule in this study. The dummy molecularly imprinted polymers coated stir bar (DMIPs-SB) showed better selectivity than the bars coated with polydimethylsiloxane or non-imprinted polymers when used to extract BPA and its three analogues. The saturated adsorption amount of the DMIPs coating was 3.0 times over that of the non-imprinted polymers coating. To achieve the optimum extraction performance, several parameters, including extraction and desorption time, pH value, adsorption temperature and stirring speed were investigated. The high-performance liquid chromatography combined with the DMIPs-SB was employed in the analysis of BPA in aqueous solution. The linear range of BPA concentration in aqueous medium was 0.0228-2.28 ng/mL with correlation coefficient of 0.9994 and the detection limit was about 6.84 × 10(-3) ng/mL based on three times ratio of signal to noise. This method was directly applied to the determination of trace BPA in milk with satisfactory results.     

Hydrophilic molecularly imprinted polymers for bisphenol A prepared in aqueous solution

We have prepared a hydrophilic molecularly imprinted polymer (MIP) for the hydrophobic compound bisphenol A (BPA) in aqueous solution using 3-acrylamido-N,N,N-trimethylpropan-1-aminium chloride (AMTC) as the functional monomer. Under redox-polymerization conditions, BPA forms an ion-pair with AMTC, which was confirmed by ¹H-NMR titration. The imprinting effect in aqueous solution was evaluated by comparison of this material with the corresponding non-imprinted polymer (NIP) and with a control polymer (CP) bearing no AMTC. The MIP showed the highest activity among the three polymers, and the imprinting factors as calculated from the amount of BPA bound to the MIP divided by the amounts bound to NIP and CP, respectively, are 1.8 and 6.0. The MIP was selective for BPA in aqueous solution, while structurally related compounds are not recognized. Such a selectivity for a hydrophobic compound is rarely observed in aqueous medium because non-specific binding of BPA inevitably leads to hydrophobic interaction.