分子印迹聚合物为涂层的吸附萃取搅拌棒在环境水样双酚A含量测定中的应用

以双酚A(BPA)为单体,利用整体材料“原位”聚合技术制备以分子印迹聚合物为涂层的吸附萃取搅拌棒(MIP-SBSE),然后与高效液相色谱(HPLC)-二极管阵列检测器联用,探讨其对环境水样BPA的选择萃取性能。优化萃取过程中吸附和解吸时间、解吸液种类以及基底pH值和离子强度对目标化合物的选择吸附性能。在最佳条件下,MIP-SBSE可对模板分子进行有效的选择吸附,线性范围为1.0～200 μg/L,检出限(S/N=3)和定量限(S/N=10)分别为0.28μg/L和0.94 μg/L。在实际水样分析中,具有良好的加标回收率,其值为96.0%～108.7%。研究结果表明,所建立的方法具有简便、灵敏和环境友好等特点。     

Dummy molecularly imprinted polymers as the coating of stir bar for sorptive extraction of bisphenol A in tap water

A unique stir bar coated with dummy molecularly imprinted polymers for bisphenol A was prepared by sol-gel technique. The scanning electron microscopic image of the coating presented a homogeneous surface with a thickness of about 57 ± 2.5 μm. The Fourier transform infrared spectrum of the coating proved the incorporating of dummy molecularly imprinted polymers with the sol-gel network. When used to extract bisphenol A from aqueous solution containing bisphenol A and its three analogs (4-tert-butylphenol, 4,4'-dihydroxybiphenyl, and 3,3',5,5'-tetrabromo-bisphenol A). Dummy molecularly imprinted polymers-coated stir bar showed better selectivity than the bars coated with polydimethylsiloxane or non-imprinted polymers. The extraction conditions including stirring speed, pH, and extraction time were optimized. After back extraction with methanol, the extracts were analyzed by high-performance liquid chromatography-fluorescence detection. The linear range was 0.0228-0.456 ng/mL with correlation coefficient of 0.9994 and the detection limit was about 5.70 × 10(-3) ng/mL based on three times ratio of signal-to-noise. The method was applied to the determination of trace bisphenol A in tap water.     

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.     

Development of selective and chemically stable coating for stir bar sorptive extraction by molecularly imprinted technique

A novel stir bar coated with molecularly imprinted polymer (MIP) as selective extraction phase for sorptive extraction of triazine herbicides was developed. The stir bar was prepared by chemically bonding the MIP to the glass bar to improve its stability. A homogeneous and porous structure was observed on the stir bar surface. Extraction performance shows that the MIP-coated stir bar has stronger affinity to the template molecule terbuthylazine as compared with that of the reference stir bar without addition of template. Owning to the shape and structural compatibility, the obtained stir bar also demonstrated specific selectivity to the structural related-compounds of nine triazines, and thus can be applied to simultaneous determination of these compounds from complex samples coupled with high performance liquid chromatography. Four complex samples with different matrix, including rice, apple, lettuce and soil were used to evaluate this proposed method. The limits of detection obtained are in the range of 0.04-0.12 μg L⁻¹, and the recoveries for the spiked rice, apple, lettuce and soil samples were 80.8-107.7%, 80.6-107.8%, 72.0-109.8% and 89.0-114.8% with RSD from 1.2 to 7.9%, respectively. Moreover, this MIP-coated stir bar was firm, durable and can be prepared simply and reproducibly. The developed coating method would be useful to prepare a range of selective stir bars in order to extend the applicability of stir bar sorptive extraction (SBSE) in complex sample analysis.     

A novel superparamagnetic surface molecularly imprinted nanoparticle adopting dummy template: An efficient solid-phase extraction adsorbent for bisphenol A

Leakage of the residual template molecules is one of the biggest challenges for application of molecularly imprinted polymer (MIP) in solid-phase extraction (SPE). In this study, bisphenol F (BPF) was adopted as a dummy template to prepare MIP of bisphenol A (BPA) with a superparamagnetic core–shell nanoparticle as the supporter, aiming to avoid residual template leakage and to increase the efficiency of SPE. Characterization and test of the obtained products (called mag-DMIP beads) revealed that these novel nanoparticles not only had excellent magnetic property but also displayed high selectivity to the target molecule BPA. As mag-DMIP beads were adopted as the adsorbents of solid-phase extraction for detecting BPA in real water samples, the recoveries of spiked samples ranged from 84.7% to 93.8% with the limit of detection of 2.50 pg mL⁻¹, revealing that mag-DMIP beads were efficient SPE adsorbents.     

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.     

Development of new polar monolithic coatings for stir bar sorptive extraction

Polar vinyl monomers have been used for the synthesis of several polymer monoliths, to serve as novel coatings for stir bar sorptive extraction; the monovinyl monomers 2‐hydroxyethyl methacrylate (HEMA) and poly(ethylene glycol) monomethacrylate) (PEGMA) were copolymerized with (apolar) divinylbenzene (DVB) and/or pentaerythritol triacrylate (PETRA), both of which are cross‐linking agents. After the optimization of the most important synthesis parameters, which included the ratio between total monomers and porogen, the nature of the porogen, and the monomer ratios, inter alia, three mechanically stable, polar monolithic coatings for stir bar sorptive extraction were obtained that were based on poly(HEMA‐co‐DVB), poly(HEMA‐co‐PETRA), and poly(PEGMA‐co‐PETRA). Thereafter, and in order to evaluate the hydrophilicity of the resulting monoliths, they were applied as materials in the stir bar sorptive extraction of a group of emerging pollutants with a wide range of polarities. The results showed that both the poly(HEMA‐co‐DVB) and poly(PEGMA‐co‐PETRA) materials could be used to extract both polar and nonpolar compounds by stir bar sorptive extraction, in an effective manner. Taking into account the desired chemical and morphological properties, as well as the extraction efficiencies, the poly(PEGMA‐co‐PETRA) material seemed to be a particularly promising monolith for application as a novel coating in stir bar sorptive extraction.     

Application of stir bar sorptive extraction for wine analysis

Stir bar sorptive extraction (SBSE) coupled with gas chromatography/mass spectrometry (GC/MS) was used to analyse wine samples for three applications: flavour and compositional analysis; 2,4,6-trichloroanisole (TCA), a common off-aroma in wine; and agrochemicals. SBSE was found to be orders of magnitude more sensitive than modern conventional methodology, allowing for lower detection and quantitation levels, and improved confirmation of identity; SBSE often gave better signal to noise in scan mode than other methods in selective ion monitoring (SIM) mode. With the help of their characteristic mass spectra all agrochemicals could be identified unambiguously at concentrations of 10 microg L(-1) in wine and a further 100 constituents were detected in a Cabernet Sauvignon sample. Thus it is now possible to analyse complex samples such as wine by scan mode, with better confirmation of identity, and without sacrificing sensitivity, where previously SIM methodology had to be used.     

分子印迹固相萃取搅拌棒的制备及对复杂样品中双烯雌酚和己烷雌酚的萃取性能

以己烯雌酚为替代模板,利用整体材料的“原位”合成技术制备了分子印迹聚合物,并将其作为固相萃取搅拌棒的涂层(MIP-SBSE)制备了新的搅拌棒。详细考察了分子印迹聚合物制备条件中模板分子及功能单体用量对MIP-SBSE选择性萃取性能的影响,同时利用元素分析、扫描电镜和红外光谱对聚合物进行表征。以双烯雌酚(DS)和己烷雌酚(HS)为目标化合物,将MIP-SBSE与高效液相色谱-二极管阵列检测器联用,建立起复杂样品中DS和HS的分离分析方法。考察了吸附和解吸时间、解吸溶剂、离子强度和样品pH值等萃取条件对MIP-SBSE选择性萃取性能的影响。结果表明,在最佳萃取条件下,MIP-SBSE对DS和HS具有较高的选择性萃取性能,线性范围分别为1.0～400.0 μg/L和5.0～400.0 μg/L,利用氮吹再定容的方法,对DS和HS的检出限(S/N=3)分别可低至0.04和0.14 μg/L。在对实际污水、蜂蜜和牛尿样品的分析中取得了良好的加标回收率,其值为61.3%～120%。所建方法具有简便、高选择性和灵敏等特点,可用于复杂样品中双烯雌酚和己烷雌酚的分析监测。     

Online desorption of molecularly imprinted stir bar sorptive extraction coupled to high performance liquid chromatography for the trace analysis of triazines in rice

Based on a special homemade interface, the molecularly imprinted stir bar sorptive extraction was coupled to high performance liquid chromatography for the online desorption and analysis. During desorption, the analytes desorbed from stir bar were delivered to a sample loop and then was introduced into liquid chromatography for further analysis. The online desorption and introduction processes were real‐time monitored by the ultraviolet detector of the liquid chromatography system. In this way, the method sensitivity and reproducibility was improved for the introduction timing of the desorption solvent with greatest concentration of the target analytes was accurately controlled. To demonstrate the feasibility of the method, terbuthylazine imprinted stir bar was synthesized and used for the analysis of nine triazines in rice. Under the optimized conditions, limits of detection of 0.02–0.11 μg/L and precision within 4.3–7.2% were achieved. The new method was compared with other two traditional offline desorption procedures, i.e. ultrasonic‐assisted desorption and static thermal desorption. The comparison results showed that the proposed method is accurate, precise, fast, and suitable for the trace analysis of complex samples.     

搅拌棒固相萃取的研究进展

作为一种新型的环境友好型样品前处理技术,搅拌棒固相萃取(SBSE)集萃取、净化和富集为一体,已经在环境监测、食品安全和生物分析等领域进行了广泛应用。本文结合作者所在研究小组的研究工作,对近几年来SBSE技术的发展进行综述,重点阐述了各种新涂层的研究和应用,同时就SBSE发展方向提出了展望。     

An alternative method for analysis of food taints using stir bar sorptive extraction

The determination of taints in food products currently can involve the use of several sample extraction techniques, including direct headspace (DHS), steam distillation extraction (SDE) and more recently solid phase microextraction (SPME). Each of these techniques has disadvantages, such as the use of large volumes of solvents (SDE), or limitations in sensitivity (DHS), or have only been applied to date for determination of individual or specific groups of tainting compounds (SPME). The use of stir bar sorptive extraction (SBSE) has been evaluated as a quantitative screening method for unknown tainting compounds in foods. A range of commonly investigated problem compounds, with a range of physical and chemical properties, were examined. The method was optimised to give the best response for the majority of compounds and the performance was evaluated by examining the accuracy, precision, linearity, limits of detection and quantitation and uncertainties for each analyte.For most compounds SBSE gave the lowest limits of detection compared to steam distillation extraction or direct headspace analysis and in general was better than these established techniques. However, for methyl methacrylate and hexanal no response was observed following stir bar extraction under the optimised conditions.The assays were carried out using a single quadrupole GC-MS in scan mode. A comparison of acquisition modes and instrumentation was performed using standards to illustrate the increase in sensitivity possible using more targeted ion monitoring or a more sensitive high resolution mass spectrometer. This comparison illustrated the usefulness of this approach as an alternative to specialised glassware or expensive instrumentation. SBSE in particular offers a ‘greener’ extraction method by a large reduction in the use of organic solvents and also minimises the potential for contamination from external laboratory sources, which is of particular concern for taint analysis.     

Recent developments in stir bar sorptive extraction

As a crucial step in qualitative and quantitative analysis, sample pretreatment is commonly used to isolate the target analytes, concentrate them, or convert them into the forms tailored to the instrumental analysis. In recent years, there has been a trend for sample pretreatment techniques to become more miniaturized and more environmentally friendly. Stir bar sorptive extraction (SBSE), which was developed in 1999, is such an environmentally friendly microextraction technique. Compared with other microextraction techniques, including solid phase microextraction and liquid phase microextraction, SBSE provides a higher extraction efficiency and better reproducibility owing to the much greater amount of the extraction phase, and no special skills are required. However, there are some problems associated with SBSE, such as the limited applicable coatings, coating abrasion of the laboratory-made stir bar, and the difficulty in automation, which restrict the further improvement and application of SBSE. This review focuses on the development of SBSE in the past decade, in terms of coating preparation, automated systems, novel extraction modes, its use with various instruments, and applications in food, environmental, and biological samples.

Novel molecularly imprinted stir bar sorptive extraction based on an 8-electrode array for preconcentration of trace exogenous estrogens in meat

A novel 8-electrode array as stir bar was designed for selective extraction of trace level exogenous estrogens from food samples, followed by liquid desorption and HPLC-photodiode array detection. The array consisted of 8 screen-printed electrodes and each electrode was modified with Fe₃O₄@meso-/macroporous TiO₂ microspheres and molecularly imprinted film (m-TiMIF). The fabrication of the imprinted film coating was very simple without organic solvents and chemical grafting. Both bisphenol A (BPA) and diethylstilbestrol (DES) were employed as templates in m-TiMIF fabrication in order to enrich both targets simultaneously. Interestingly, the imprinted stir bar array showed higher extraction capacity and selectivity for BPA and DES than the non-imprinted counterpart. Meanwhile, it exhibited fast adsorption and desorption kinetics due to increased mass transport in the ultra-thin film. Importantly, the m-TiMIF coating was robust enough for at least 20 uses without obvious alteration in extraction performance. The main parameters affecting the extraction efficiency, including stir speeding, sample pH, ionic strength, extraction time, desorption solvent and time, were optimized. Under optimal experimental conditions, the limits of detection (S/N = 3) of the developed method were 0.28 and 0.47 μg L⁻¹ for BPA and DES respectively, with enrichment factors of 32.6 and 52.8-fold. The linear ranges were 3.0–1500 μg L⁻¹ and 4.0–1500 μg L⁻¹ for BPA and DES, respectively. The m-TiMIF-coating conferred better recovery and selectivity, compared with the commercial stir bar coating. The new method was successfully applied to assess BPA and DES in pork and chicken samples with satisfactory recovery.     

Preparation of a molecularly imprinted polymer for the solid-phase extraction of scopolamine with hyoscyamine as a dummy template molecule

Molecularly imprinted polymers (MIPs) selective for scopolamine were produced using hyoscyamine (a close structural analogue) as template molecule. The produced polymers were used as media for solid-phase extraction, exhibiting selective binding properties for the analyte from biological samples. Human and calf urine and serum were processed on the MIP under various extraction protocols. The best performance was observed after loading the analyte in aqueous environment facilitating retention on the MIP by non-selective hydrophobic interactions. The MIPs were subsequently washed using an optimised solvent system to enable selective desorption of the analyte. Other related and non-related compounds were accessed to evaluate molecular recognition properties. Recoveries of up to 79% were achieved for the analyte of interest from biological samples.     

Molecularly imprinted stir bar sorptive extraction coupled with high-performance liquid chromatography for trace analysis of naphthalene sulfonates in seawater

In this paper, a novel molecularly imprinted polymer coated stir bar has been used to selectively extract naphthalene sulfonates (NS_s) directly from seawater sample. 1-Naphthalene sulfonic acid (1-NS) was used as template molecule. The effects of different parameters were optimized on the extraction efficiency and the optimum conditions were established as: the absorption and desorption times were fixed, respectively, at 10 and 15 min, stirring speed was 700 rpm, pH was adjusted to 4.1, amount of NaCl was 1 mol L^?1 and extraction process was performed at a temperature of 50 °C. The linear ranges were 2–250 µg L^?1 for 3,6-NDS-1-OH (1-naphthol-3,6-disulfonic acid), 4–250 µg L^?1 for 2-NS (2-naphthalene sulfonate) and 3–250 µg L^?1 for 1-NS. The detection limits were within the range of 0.32–0.95 µg L^?1. Under optimum conditions, the detection limits of the NSs were 0.84, 0.95 and 0.32 µg L^?1 with the enrichment factor of 117-, 41- and 77-fold for 2-NS, 1-NS, and 6-NDS-1-OH, respectively. The repeatability of the method was satisfactory (0.53 ≤ RSD ≤6.0 %, n = 10). The method has been successfully applied for the analysis of trace amounts of three naphthalene sulfonates in seawater of Chabahar Bay.     

微囊藻毒素分子印迹搅拌棒涂层的研制及其吸附性能

以微囊藻毒素(MC)-LR为模板,甲基丙烯酸(MAA)为功能单体,通过可逆加成-断裂链转移(RAFT)自由基聚合技术,在凹凸棒土(ATP)表面制备了磁性分子印迹聚合物,并通过溶胶-凝胶法将分子印迹聚合物作为涂层介质制作搅拌棒。同时通过红外吸收光谱和扫描电镜等对印迹聚合物进行了结构和形貌的表征,并用液相色谱研究了搅拌棒涂层对水体中微囊藻毒素的吸附性能。结果表明,在最佳萃取条件下,分子印迹搅拌棒涂层对MC-LR具有较高的选择性能,在0.010~5.0 mg/L范围内线性关系良好(r²>0.997),检出限(S/N=3)可低至0.27 μg/L。MC-LR加标水平为20.0~80.0 μg/L的回收率范围为83.33%~100.07%,相对标准偏差(RSD)为1.40%~9.17%。该方法快速、灵敏、选择性高,可用于环境水体中微囊藻毒素的分析检测。     

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.     

Optimisation of stir bar sorptive extraction for the analysis of volatile phenols in wines

An easy, fast and reliable analytical method is proposed for the determination of the concentration of volatile phenols (ethyl- and vinylphenols) in wines. The novel stir bar sorptive extraction (SBSE) technique is employed, following a simple and fast procedure that allows 15 samples to be extracted simultaneously using very small sample volume. Extracts are desorbed in a thermodesorption system (TDS) coupled on-line to a gas chromatograph-mass spectrometry system. The SBSE offers better recovery and linear regression coefficient (r2) for the four volatile phenols than solid-phase extraction (SPE). The mass spectrometric detection in selected ion monitoring mode contributes to the lower detection limit and good sensibility obtained with this method.     

表面分子印迹磁性固相萃取-液相色谱-荧光光谱法测定河水中双酚A

通过原子转移自由基聚合(Atom Transfer Radical Polymerization-ATRP)法制备核壳结构单分散性磁性亚微米粒子( Fe304@ MIPs),并建立了磁性固相萃取-高效液相色谱荧光光谱(MSPE- HPLC - FLD)测定河水中环境类雌激素 双酚A (BPA)的方法.利用透射...