The application of pseudo template molecularly imprinted polymer to the solid-phase extraction of cyromazine and its metabolic melamine from egg and milk

The combination of molecularly imprinted polymer with high performance liquid chromatography has been developed to determine cyromazine and its metabolic melamine in some samples. However, the potential risk of template leakage used in molecularly imprinted polymer is a major disadvantage. To solve this problem, 2-(4,6-diamino-1,3,5-triazin-2-ylamino) ethanethiol disulfide, a molecule that shares the similar imprinting sites with cyromazine and melamine, was selected as pseudo template to prepare molecularly imprinted polymer. Methacrylic acid, ethylene glycol dimethyl acrylate and toluene were selected as functional monomer, crosslinker and porogen, respectively. The molecular recognition property and binding capability of cyromazine and melamine were evaluated by adsorption test and Scatchard analysis. The results showed that the molecularly imprinted polymer based on pseudo template had more excellent affinity and selectivity for cyromazine and melamine. The resulting molecularly imprinted polymer was used as a solid-phase extraction material to enrich cyromazine and melamine in egg and milk samples for high performance liquid chromatography analysis. The solid-phase extraction process was carefully optimized. It was found that when different concentration of cyromazine and melamine standards were spiked into samples, satisfactory recovery rate of cyromazine and melamine were obtained as 85.6-98.8% with relative standard deviation <5.5%.     

Determination of Chlorogenic Acid and Rutinum in Herba Artemisiae Scopariae with Multitemplate Molecularly Imprinted Polymers for Solid-phase Extraction with High-performance Liquid Chromatography

Novel multitemplate molecularly imprinted polymers were prepared using mixtures of chlorogenic acid and rutinum as molecular templates, acrylamide as a functional monomer, divinylbenzene as the cross-linker, and 20:80 methanol:acetone as the porogen. The polymers were assessed for solid-phase extraction (SPE) for the purification of two compounds from Herba Artemisiae Scopariae. The synthesized molecularly imprinted polymers were identified by infrared spectroscopy and scanning electron microscopy. Systematic characterization of the functional monomer and porogens on the recognition properties of the molecularly imprinted polymers were carried out. Comparison with single-template molecularly imprinted polymers showed that the multitemplate molecular polymers exhibited higher selectivity and adsorption capacity for multiple analytes. The optimization of washing solvent as 1:9 acetone:water and the elution solvent as 9:1 acetonitrile:acetic acid provided a reliable analytical method with strong recognition toward multiple analytes in Herba Artemisiae Scopariae extracts with satisfactory recoveries of 89.6% for chlorogenic acid and 93.8% for rutinum. These results demonstrate that the multitemplate molecularly imprinted polymers coupled with SPE are effective for the selective purification of bioactive compounds in complex samples.     

Selective Preconcentration of Mezlocillin from Eggs by Molecularly Imprinted Polymers on Silica

Surface molecularly imprinted polymers for mezlocillin were used for the selective solid-phase extraction of mezlocillin from eggs. The molecularly imprinted polymers were prepared using mezlocillin as the template, methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker, silica particle as the support and were characterized by infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The adsorption properties of polymers were investigated in detail. The obtained polymers provided high imprinting efficiency to mezlocillin with an imprinting factor of 3.72 and were used as selective sorbents for mezlocillin. Molecularly imprinted solid-phase extraction followed by high-performance liquid chromatography was used for the determination of mezlocillin in eggs and the conditions were evaluated. The average recovery of mezlocillin in fortified eggs was between 69.8 and 82.3% with a relative standard deviation less than 6.9%. The results demonstrate the application of molecularly imprinted polymers for the extraction of mezlocillin from biological samples.     

分子印迹固相萃取—高效液相色谱法同时测定鸡血浆中环丙氨嗪和三聚氰胺残留

建立了基于分子印迹固相萃取-高效液相色谱同时测定鸡血浆中环丙氨嗪和三聚氰胺残留方法.以环丙氨嗪为模板分子,甲基丙烯酸为功能单体,合成了对环丙氨嗪和三聚氰胺具有高选择性的分子印迹聚合物.作为固相萃取填料,评价和优化了其分离、富集环丙氨嗪和三聚氰胺的固相萃取条件.血浆用1％三氯乙酸沉淀蛋白,分子印迹固相萃取净化.在辛烷磺酸...     

Extraction of Anthraquinones from Rhubarb by a Molecularly Imprinted–Matrix Solid-Phase Dispersion Method with HPLC Detection

A simple method based on matrix solid-phase dispersion for selective extraction of anthraquinones from rhubarb samples was developed using a molecularly imprinted polymer as sorbent. The molecularly imprinted polymer was prepared using emodin as the template molecule, methacrylic acid as the functional monomer, and ethylene glycol dimethacrylate as the cross-linking agent. The polymer was characterized by scanning electron microscopy and Fourier-transform infrared spectrometry. Isothermal adsorption and dynamic adsorption experiments were performed. The best extraction conditions for anthraquinones were obtained at a ratio of molecularly imprinted polymer to sample of 1:1, a dispersion time of 5 minutes, with 5% aqueous methanol as the washing solvent, and an elution solvent of methanol-acetic acid (99:1, v/v). Once the matrix solid-phase dispersion process was optimized, the extract was reacted with 8% hydrochloric acid for hydrolysis. The anthraquinones extracted from rhubarb were determined by liquid chromatography. The detection limits of chrysophanol, emodin, physcion, and aloe-emodin were 0.23, 0.24, 0.28, and 0.27 µg mL^?1, respectively. The proposed method was compared with the method in Chinese pharmacopoeia, and the results show that the extraction yield of anthraquinones obtained by molecularly imprinted polymer–matrix solid-phase dispersion method was higher. Moreover, the proposed method is faster and simpler and can achieve extraction and purification in the same system.     

分子印迹固相萃取技术在动物源食品中药物残留检测应用进展

以分子印迹材料作为特效吸附剂的分子印迹固相萃取技术具有从复杂样品中选择性吸附目标分子及其结构类似物的能力,较好地克服了由于样品复杂所带来的内源性干扰问题,因此非常适用于复杂样品的预处理与富集。本文介绍了分子印迹固相萃取技术的原理、最新进展以及相关萃取参数的优化过程,对近几年国内外分子印迹固相萃取技术在动物源食品中药物残留检测方面的应用进行了总结;阐明了分子印迹固相萃取技术在实际应用中存在的不足,并对其未来的发展进行了展望。     

Preparation and evaluation of molecularly imprinted microspheres for solid-phase extraction of 1,4-hydroxybenzoic acid esters in soy

Molecularly imprinted microspheres (MIMs) were prepared by precipitation polymerization for the binding and recognition of 1,4-hydroxybenzoic acid esters. Ethyl p-hydroxybenzoate (EtPHB) was used as the template molecule, methacrylic acid as the functional monomer, ethylene dimethacrylate as the linking agent. It was evaluated by solid-phase extraction column packed with MIMs combined with liquid chromatography to determine trace preservatives including benzoic acid, methyl p-hydroxybenzoate, EtPHB, propyl p-hydroxybenzoate in food products. A solid-phase extraction based on MIM procedure was used to isolate four additives from the food matrix before quantitative analysis. The Scatchard plot suggested that the template-polymer system had two-site binding behavior with the dissociation constants of 0.3577 and 3.952 mg/g, respectively. The rebinding test, based on the molecularly imprinted solid-phase extraction column technique, showed the recoveries of soy samples spiked with four additives within 88.4-110.6%, with the relative standard deviations of 1.97-3.82%. Finally, the method was successfully applied for the analysis of parabens in foodstuff without traditional pretreatment.     

Solid-phase extraction of esculetin from the ash bark of Chinese traditional medicine by using molecularly imprinted polymers

A molecularly imprinted polymer solid-phase extraction method is used to extract esculetin from the ash bark of Chinese traditional medicine. Ratio of ethanol and water as washing solution were investigated. Data of accumulative adsorption on molecularly imprinted polymers from the continuous loading experiment suggests that there are two different kinds of recognition sites in molecularly imprinted polymers. By selecting the washing and eluting solution a scheme was designed to separate esculetin and its analogues including esculin, coumarin, 7-methoxylcoumarin and daphnetin. Finally, by applying the revised scheme esculetin was extracted from the ash bark of Chinese traditional medicine that was purchased from two big drugstores, respectively, with both molecularly imprinted polymers and non-molecularly imprinted polymers.     

Determination of pharmaceuticals in wastewaters using solid-phase extraction-liquid chromatography-tandem mass spectrometry

Four different commercial sorbents for solid-phase extraction have been evaluated for the extraction of a group of acidic pharmaceuticals in terms of selectivity and capacity: Oasis hydrophilic-lipophilic balance (HLB), Oasis MAX (strong anion exchange), Oasis WAX (weak anion exchange) and a commercial available molecularly imprinted polymer specific for non-steroidal anti-inflammatory drugs. Among the sorbents studied, molecularly imprinted polymer proved to be very effective in the reduction of matrix interferences and the selective extraction of acidic pharmaceuticals, such as salicylic acid, ibuprofen, fenoprofen, diclofenac and naproxen, among others, from effluent wastewater samples. Moreover, molecularly imprinted solid-phase extraction protocol was applied to liquid chromatography coupled to tandem mass spectrometry (MS/MS) with the purpose of evaluating the clean-up effect on ion suppression/enhancement when the complexity of the samples increases and a reduction of this effect was observed. Molecularly imprinted solid-phase extraction followed by liquid chromatography coupled to ultraviolet detection and liquid chromatography coupled to tandem mass spectrometry validation methodologies with effluent wastewaters were developed, obtaining recoveries between 70 and 85% and limits of detection at low levels of μg/L (0.15-1 μg/L) and ng/L (0.5-2 ng/L), respectively. The final application of molecularly imprinted solid-phase extraction and liquid chromatography coupled to MS/MS detection showed the presence of acidic pharmaceuticals studied in this work in effluent wastewaters (相似文献   

分子印迹技术制备石油有机硫组分固相萃取剂的研究

用分子印迹技术合成了对石油有机硫组分二苯并噻吩(Dibenzothiophene，DBT)具有高效选择性的分子模板聚合物(Molecularly Imprinted Polymer，MIP)，通过静态吸附的方法研究了不同功能单体和致孔剂及其用量对模板聚合物特异性识别能力的影响．实验表明，以4-乙烯基吡啶(4-VP)为功能单体，在甲苯溶剂中聚合得到的固相萃取剂对DBT具有较大的吸附富集能力和识别特性．其饱和吸附容量达到48．3mg／g．     

Synthesis and Characterization of a Molecularly Imprinted Polymer for Preconcentration of Clothianidin in Environmental Samples

A molecularly imprinted polymer for the selective solid-phase extraction of clothianidin was prepared using the analyte as a template, methacrylic acid and styrene as functional monomers, ethylene glycol dimethacrylate as the cross-linker, acetonitrile as a porogen, and 2,2-azobisisobutyronitrile as an initiator. The polymer was characterized by scanning electron microscopy and infrared spectroscopy. Adsorption measurements indicated that the molecularly imprinted polymers exhibited good recognition ability and fast dynamics toward clothianidin. Using this imprinted polymer as a sorbent, a new method of molecularly imprinted solid phase extraction coupled to high performance liquid chromatography for the determination of clothianidin residues was developed. The molecularly imprinted solid phase extraction procedure was optimized to purify and enrich clothianidin residues in river water, soil, tomatoes, grapes, and Chinese cabbage. The average recoveries of clothianidin spiked at 0.005 to 0.05 mg/L were 84.32 to 89.49% in river water with a relative standard deviation 2.22 to 4.79% (n = 3). The average recoveries of clothianidin spiked at 0.05 to 0.5 mg/kg were 85.49 to 96.36% in soil, grapes, Chinese cabbage, and tomatoes, with a relative standard deviation of 2.40 to 6.02% (n = 3). Overall, this study provides a sensitive and effective method for the accurate determination of clothianidin residues in environmental samples.     

Selective separation of active inhibitors of epidermal growth factor receptor from Caragana jubata by molecularly imprinted solid-phase extraction

A feasibility research was performed to study the possibilities of using a molecularly imprinted polymer as sorbent material in solid-phase extraction for the separation of active inhibitors of epidermal growth factor receptor (EGRF) from Caragana Jubata, a Chinese traditional Tibetan medicine. A molecularly imprinted polymer using quercetin, an active anti-EGFR inhibitor (IC50 = 15 microM), as the template and acrylamide as the functional monomer was prepared. The polymer was evaluated as a selective sorbent in molecularly imprinted solid-phase extraction. The EtOAc extract of Caragana Jubata was loaded on the polymer, and two novel active anti-EGFR inhibitors were found to be selectively retained after washing the polymer with appropriate solvent to disrupt the non-specific interactions occurring between the sample and the polymer matrix, which were identified as (E)-piceatannol (IC50 =4.9 microM) and butein (IC50 = 10 microM). The present work affords us a new potential method for selective separation of bioactive components from herb by using molecularly imprinted polymer as a solid-phase extraction adsorbent.     

Evaluation of 2-hydroxyethyl methacrylate as comonomer in the preparation of water-compatible molecularly imprinted polymers for triazinic herbicides

In this work, the preparation and evaluation of water-compatible molecularly imprinted polymers for triazines using 2-hydroxyethyl methacrylate and methacrylic acid as comonomers is described. Four sets of molecularly imprinted and non-imprinted polymers for propazine were prepared at varying monomer molar ratios (from 4:0 to 1:3), and evaluated for the recognition of several triazines directly in aqueous media. The evaluation was performed by loading 1 mL of an aqueous solution containing 500 ng of each selected triazine, washing with 500 μL of acetonitrile, and eluting with 500 μL of methanol followed by 2 × 500 μL of a solution of methanol containing 10% of acetic acid. Final determinations were performed by high-performance liquid chromatography-ultraviolet detection. Improvement in molecular recognition of triazines in water was obtained on those molecularly imprinted polymers incorporating 2-hydroxyethyl methacrylate in 3:1 or 2:2 molar ratios, being the former selected as optimum providing recoveries for propazine up to 80%. A molecularly imprinted solid-phase extraction protocol was developed to ensure that triazines-selective recognition takes place inside selective binding sites in pure water media. Finally, the developed method was successfully applied to the determination of the selected triazines in environmental waters providing limits of detection from 0.16 and the 0.5 μg/L concentration range.     

Molecularly imprinted solid-phase extraction for the selective determination of methamphetamine, amphetamine, and methylenedioxyphenylalkylamine designer drugs in human whole blood by gas chromatography-mass spectrometry

A novel method is described for the extraction of methamphetamine, amphetamine, and methylenedioxyphenylalkylamine designer drugs, such as 3,4-methylenedioxy-methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxyethylamphetamine, N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine, and 3,4-(methylenedioxyphenyl)-2-butanamine, from human whole blood using molecularly imprinted solid-phase extraction as highly selective sample clean-up technique. Whole blood samples were diluted with 10 mmol/L ammonium acetate (pH 8.6) and applied to a SupelMIP-Amphetamine molecularly imprinted solid-phase extraction cartridge. The cartridge was then washed to eliminate interferences, and the amphetamines of interest were eluted with formic acid/methanol (1:100, v/v). After derivatization with trifluoroacetic anhydride, the analytes were quantified using gas chromatography-mass spectrometry. Recoveries of the seven amphetamines spiked into whole blood were 89.1-102%. The limits of quantification for each compound in 200 μL of whole blood were between 0.25 and 1.0 ng. The maximum intra- and inter-day coefficients of variation were 9.96 and 13.8%, respectively. The results show that methamphetamine, amphetamine, and methylenedioxyphenylalkyl-amine designer drugs can be efficiently extracted from crude biological samples such as whole blood by molecularly imprinted solid-phase extraction with good reproducibility. This extraction method will be useful for the pretreatment of human samples before gas chromatography-mass spectrometry.     

Exploration of a ternary deep eutectic solvent of methyltriphenylphosphonium bromide/chalcone/formic acid for the selective recognition of rutin and quercetin in Herba Artemisiae Scopariae

Methyltriphenylphosphonium bromide/chalcone/formic acid, a green ternary deep eutectic solvent, was applied as a functional monomer and dummy template simultaneously in the synthesis of a new molecularly imprinted polymer. Ternary deep eutectic solvent based molecularly imprinted polymers are used as a solid‐phase extraction sorbent in the separation and purification of rutin and quercetin from Herba Artemisiae Scopariae combined with high‐performance liquid chromatography. Fourier transform infrared spectroscopy and field‐emission scanning electron microscopy were applied to characterize the deep eutectic solvent based molecularly imprinted polymers synthesized using different molar ratios of chalcone. The static and competitive adsorption tests were performed to examine the recognition ability of the molecularly imprinted polymers to rutin and quercetin. The ternary deep eutectic solvent consisting of formic acid/chalcone/methyltriphenylphosphonium bromide (1:0.05:0.5) had the best molecular recognition effect. After optimization of the washing solvents (methanol/water, 1:9) and eluting solvents (acetonitrile/acetic acid, 9:1), a reliable analytical method was developed for strong recognition towards rutin and quercetin in Herba Artemisiae Scopariae with satisfactory extraction recoveries (rutin: 92.48%, quercetin: 94.23%). Overall, the chalcone ternary deep eutectic solvent‐based molecularly imprinted polymer coupled with solid‐phase extraction is an effective method for the selective purification of multiple bioactive compounds in complex samples.     

Preparation and Evaluation of Propranolol-Imprinted Monolithic Stationary Phase by In Situ Technique and Application in Analysis of Propranolol in Biological Samples

Abstract

A propranolol molecule-imprinted monolithic stationary phase (MIMSP) was synthesized by in situ technique. The recognition mechanism of the polymers and the influences of some chromatographic conditions were examined by high-performance liquid chromatography (HPLC). The imprinted polymers showed much higher selectivity for β-blockers than the nonimprinted polymers (NIPs) did, which proves the successful preparation of propranolol-imprinted polymers by using an in situ technique. Then, this technique was used to prepare a molecularly imprinted polymer solid-phase extraction column to concentrate propranolol from biological samples. The results showed that the imprinted solid-phase extraction column could selectively enrich and purify propranolol from biological samples, such as plasma.     

吡哌酸分子印迹聚合物的分子识别

采用分子印迹技术合成了吡哌酸分子印迹聚合物。运用平衡结合实验研究了聚合物的吸附特性和选择性识别能力。Scatchard分析表明,在本文所研究的浓度范围内,聚合物中形成了两类不同的结合位点。吡哌酸分子印迹聚合物对吡哌酸呈现较高的选择识别特性,可作为固相萃取剂,在人血清吡哌酸的分析中对样品进行了有效的提取和净化。     

Magnetic molecularly imprinted polymers for recognition and enrichment of polysaccharides from seaweed

New magnetic molecularly imprinted polymers with two templates were fabricated for the recognition of polysaccharides (fucoidan and alginic acid) from seaweed by magnetic solid‐phase extraction, and the materials were modified by seven types of deep eutectic solvents. It was found that the deep eutectic solvents magnetic molecularly imprinted polymers showed stronger recognition and higher recoveries for fucoidan and alginic acid than magnetic molecularly imprinted polymers, and the deep eutectic solvents‐4‐magnetic molecularly imprinted polymers had the best effects. The practical recovery of the two polysaccharides (fucoidan and alginic acid) purified with deep eutectic solvents‐4‐magnetic molecular imprinted polymers in seaweed under the optimal conditions were 89.87, and 92.0%, respectively, and the actual amounts extracted were 20.6 and 18.7 μg/g, respectively. To sum up, the developed method proved to be a novel and promising method for the recognition of complex polysaccharide samples from seaweed.