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1.
A new three‐dimensional graphene oxide‐wrapped melamine foam was prepared and used as a solid‐phase extraction substrate. β‐Cyclodextrin was fabricated onto the surface of three‐dimensional graphene oxide‐wrapped melamine foam by a chemical covalent interaction. In view of a specific surface area and a large delocalized π electron system of graphene oxide, in combination with a hydrophobic interior cavity and a hydrophilic peripheral face of β‐cyclodextrin, the prepared extraction material was proposed for the determination of flavonoids. In order to demonstrate the extraction properties of the as‐prepared material, the adsorption energies were theoretically calculated based on periodic density functional theory. Static‐state and dynamic‐state binding experiments were also investigated, which revealed the monolayer coverage of flavonoids onto the β‐cyclodextrin/graphene oxide‐wrapped melamine foams through the chemical adsorption. 1H NMR spectroscopy indicated the formation of flavonoids–β‐cyclodextrin inclusion complexes. Under the optimum conditions, the proposed method exhibited acceptable linear ranges (2–200 μg/L for rutin and quercetin‐3‐O‐rhamnoside; 5–200 μg/L for quercetin) with correlation coefficients ranging from 0.9979 to 0.9994. The batch‐to‐batch reproducibility (= 5) was 3.5–6.8%. Finally, the as‐established method was satisfactorily applied for the determination of flavonoids in Lycium barbarum (Goji) samples with relative recoveries in the range of 77.9–102.6%.  相似文献   

2.
Considering the importance of developing a new analytical approach for pesticide residue detection for the sake of ensuring food safety, a β‐cyclodextrin based molecularly imprinted polymer was prepared for selective determination of carbendazim. The polymers consist of a porous and hollow structure demonstrating the selective abundant adsorption sites for carbendazim molecule. The selectivity and adsorption capacity of the imprinted polymers were analyzed with dispersive solid‐phase extraction and analyzed with high performance liquid chromatography coupled with ultraviolet. The results of imprinted polymers were higher than non‐imprinted polymers with the maximum adsorption capacity of 3.65 mg/g within 30 min of total adsorption time. The reusability of the imprinted polymers was determined to evaluate its effectiveness and stability, which proved that the polymers lost 10% efficiency within seven consecutive recycles. The developed method displayed good linearity over the concentration range of 0.05–2.0 mg/L. The recovery percentage of 81.33–97.23 with relative standard deviations of 1.49–4.66% was obtained from spiked apple, banana, orange, and peach samples with a limit of detection of 0.03 mg/L and a limit of quantification of 0.10 mg/L (signal to noise ratio = 3/10). The overall performance of the proposed method evident that this technique provided a desirable outcome and it can be used as a convenient approach, as it qualifies the analytical standards.  相似文献   

3.
A polymeric column that contains multiwalled carbon nanotubes‐β‐cyclodextrin composite was developed. The composite was wrapped into the poly(butyl methacrylate‐ethylene dimethacrylate) monolith column (0.76 mm id and 10 cm in length). The column was then applied for the online solid‐phase microextraction of psoralen and isopsoralen from Fructus Psoraleae. Following microextraction, the coumarins were quantified by high‐performance liquid chromatography with C18 separation column and UV detection. The effects of sample flow rate, sample volume, and pH value were optimized. The method showed low limits of detection (20 pg/mL, S/N = 3) for both psoralen and isopsoralen. Finally the method was successfully applied to the determination of psoralen and isopsoralen in spiked herb extracts and rat plasma where it gave recoveries that ranged between 93.2 and 102.1%. The empty hydrophobic cavities of β‐cyclodextrin and the hydrophobicity of multiwalled carbon nanotubes provided specific extraction capability for psoralen and isopsoralen.  相似文献   

4.
A novel method was developed to simultaneously determine the ciprofloxacin and levofloxacin levels in human urine using an ionic‐liquid‐based, dual‐molecularly imprinted polymer‐coated graphene oxide solid‐phase extraction monolithic column coupled with high‐performance liquid chromatography. The molecularly imprinted monolithic column was prepared using ciprofloxacin and levofloxacin as templates, 1‐vinyl‐3‐ethylimidazolium bromide as the functional monomer, and graphene oxide as the core material. The resulting imprinted monoliths were characterized by scanning electron microscopy and fourier transform‐infrared spectroscopy. The efficiency and capacity of the ionic‐liquid‐based imprinted monolithic column were investigated by varying the synthesis conditions (ciprofloxacin/levofloxacin ratio and template/functional monomer/cross‐linker ratio). The solid‐phase extraction process was optimized by changing the washing and eluting conditions. The results suggested that the proposed ionic‐liquid‐based molecularly imprinted solid‐phase extraction monolithic‐high‐performance liquid chromatography method could separate ciprofloxacin and levofloxacin efficiently and simultaneously from human urine. The mean recoveries of ciprofloxacin and levofloxacin ranged from 89.2 to 93.8 and 86.7 to 94.6%, respectively. The intra‐ and interday relative standard deviation ranged from 0.9 to 3.2 and 0.8 to 2.9%, respectively. Under the optimized conditions, the recoveries of ciprofloxacin and levofloxacin were more than 93.8%.  相似文献   

5.
In this study, novel monodisperse restricted access media‐molecularly imprinted polymers were successfully prepared by surface initiated reversible addition‐fragmentation chain transfer polymerization using monodisperse crosslinked poly (glycidyl methacrylate‐co‐ethylene glycol dimethacrylate) microspheres as the carrier and acryloyl chloride‐modified β‐cyclodextrin as the hydrophilic functional monomer. The surface morphology, protein exclusion, and adsorption properties of the molecularly imprinted polymers were investigated. The results show that the material has excellent monodispersity and hydrophilicity, and simultaneously exhibit high adsorption capacity, fast binding kinetics, high selectivity, and significant thermal stability. The molecularly imprinted polymers as dispersive solid‐phase extraction adsorbent combined with reversed‐phase high‐performance liquid chromatography was used to selectively enrich, separate, and analyze trace 17β‐estradiol in milk samples. The recovery of 17β‐estradiol is 88–95% with relative standard deviation of <4%, and the limits of detection and quantification of this method are 2.08 and 9.29 µg/L, respectively. The novel restricted access media‐molecularly imprinted polymer adsorbents provide an effective method for the selective extraction and detection of 17β‐estradiol directly from complex samples.  相似文献   

6.
Photoirradiation surface molecularly imprinted polymers for the separation of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin were synthesized using functionalized silica as a matrix, 4‐(phenyldiazenyl)phenol as a light‐sensitive monomer, and 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin as a template. Fourier transform infrared spectroscopy results indicated that 4‐(phenyldiazenyl)phenol was grafted onto the surface of functionalized silica. The obtained imprinted polymers exhibited specific recognition toward 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin. Equilibrium binding experiments showed that the photoirradiation surface molecularly imprinted polymers obtained the maximum adsorption amount of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin at 20.5 mg/g. In binding kinetic experiments, the adsorption reached saturation within 2 h with binding capacity of 72.8%. The experimental results showed that the adsorption capacity and selectivity of imprinted polymers were effective for the separation of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin, indicating that imprinted polymers could be used to isolate 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin from a conversion mixture containing β‐cyclodextrin and maltose. The results showed that the imprinted polymers prepared by this method were very promising for the selective separation of 6‐O‐α‐d ‐maltosyl‐β‐cyclodextrin.  相似文献   

7.
Magnetic graphene oxide was modified by four imidazole‐based ionic liquids to synthesize materials for the extraction of polysaccharides by magnetic solid‐phase extraction. Fucoidan and laminarin were chosen as the representative polysaccharides owing to their excellent pharmaceutical value and availability. Fourier transform infrared spectroscopy, field‐emission scanning electron microscopy, and thermogravimetric analysis were applied to characterize the synthesized materials. Single‐factor experiments showed that the extraction efficiency of polysaccharides was affected by the amount of ionic liquids for modification, solid–liquid ratio of brown alga and ethanol, the stirring time of brown alga and ionic liquid‐modified magnetic graphene oxide materials, and amount of 1‐(3‐aminopropyl)imidazole chloride modified magnetic graphene oxide materials added to the brown alga sample solution. The results indicated that 1‐(3‐aminopropyl)imidazole chloride modified magnetic graphene oxide possessed better extraction ability than graphene oxide, magnetic graphene oxide, and other three ionic‐liquid‐modified magnetic graphene oxide materials. The highest extraction recoveries of fucoidan and laminarin extracted by 1‐(3‐aminopropyl)imidazole chloride modified magnetic graphene oxide were 93.3 and 87.2%, respectively. In addition, solid materials could be separated and reused easily owing to their magnetic properties.  相似文献   

8.
合成了以纳米材料氧化石墨烯为载体的表面分子印迹固相萃取材料,建立了分子印迹萃取联用高效液相色谱法检测牛奶塑料包装袋中的塑化剂邻苯二甲酸二(2-乙基己)酯(DEHP)残留的方法。以氧化石墨烯为基质、DEHP为模板分子、甲基丙烯酸为功能单体、N,N-二甲基甲酰胺为溶剂,通过沉淀聚合法合成表面分子印迹材料,优化了合成条件并对产品进行红外光谱、透射电镜表征。对产品的吸附性能(包括选择性、吸附平衡时间、吸附容量、重复使用率等)进行测定。在最优萃取条件下对牛奶包装袋提取液中DEHP进行选择性富集,通过高效液相色谱-紫外法检测,线性范围为0.5~50 mg/L,检出限为0.03 mg/L,定量限为0.1 mg/L。3种加标浓度下回收率为81.6%~92.4%,相对标准偏差(RSDs)小于7%。结果表明,该方法能够应用于实际样品中DEHP分析。  相似文献   

9.
l ‐Kynurenine is an endogenous metabolite generated by the catabolic pathway of l ‐tryptophan and it could be a potential biomarker to test the efficacy of several checkpoint inhibitors that have already reached the clinical trials in the antitumor therapy. Thus, a molecularly imprinted polymer specific for the recognition of this metabolite was synthesized and used as innovative system in solid‐phase extraction technique for the specific extraction and quantification of l ‐kynurenine in human urine. The off‐line system was firstly tested on l ‐kynurenine standard solutions, allowing recoveries up to 97.7% (relative standard deviation = 2.2%) and then applied to fortified and deproteinated human urine samples, where a recovery of 84.1% (relative standard deviation = 3.1%) was obtained. The method was validated and it revealed a good linearity in the range of 0.157–20 μg/mL (r= 0.9992). The optimized procedure demonstrated a good feasibility on biological samples, allowing a ready quantification of l ‐kynurenine in the human urine, where the metabolite was found at a very low concentration (0.80 μg/mL). The extraction system developed could attract attention of pharmaceutical industries for l ‐kynurenine production as potential drug in the treatment of autoimmune disorders through its extraction and purification from biological matrixes.  相似文献   

10.
In this study, a simple effervescence‐assisted dispersive solid‐phase extraction method was developed to detect fungicides in honey and juice. Most significantly, an innovative ionic‐liquid‐modified magnetic β‐cyclodextrin/attapulgite sorbent was used because its large specific surface area enhanced the extraction capacity and also led to facile separation. A one‐factor‐at‐a‐time approach and orthogonal design were employed to optimize the experimental parameters. Under the optimized conditions, the entire extraction procedure was completed within 3 min. In addition, the calibration curves exhibited good linearity, and high enrichment factors were achieved for pure water and honey samples. For the honey samples, the extraction efficiencies for the target fungicides ranged from 77.0 to 94.3% with relative standard deviations of 2.3–5.44%. The detection and quantitation limits were in the ranges of 0.07–0.38 and 0.23–1.27 μg/L, respectively. Finally, the developed technique was successfully applied to real samples, and satisfactory results were achieved. This analytical technique is cost‐effective, environmentally friendly, and time‐saving.  相似文献   

11.
A novel polymeric monolith column with a  β‐cyclodextrin‐graphene composite was prepared for extraction of methyl jasmonate. A simple, sensitive, and effective polymeric monolith microextraction with high‐performance liquid chromatography method has been presented for the determination. To carry out the best microextraction efficiency, several parameters such as sample flow rate, sample volume, and sample pH value were systematically optimized. In addition, the method validation showed a wide linear range of 5–2000 ng/mL, with a good linearity and low limits of detection for methyl jasmonate. The proposed method was successfully applied for the determination of methyl jasmonate in wintersweet flowers with recoveries of 90.67%. The result was confirmed by high‐performance liquid chromatography with mass spectrometry.  相似文献   

12.
Novel molecularly imprinted chitosan microspheres were prepared on the surface of magnetic graphene oxide, with deep eutectic solvents both as a functional monomer and template. The prepared molecularly imprinted chitosan microspheres‐magnetic graphene oxide was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, Brunauer‐Emmett‐Teller surface area, thermogravimetric analysis were subsequently combined with solid‐phase micro‐extraction for simultaneous separation and enrichment of the extraction of chlorophenols from environmental water. Factors affecting the extraction efficiency of chlorophenols were optimized using response surface methodology. The actual extraction capacities under the optimal conditions (liquid to solid ratio = 3, cycles of adsorption/desorption = 5, 40°C extraction temperature, and extraction time for 35 min) were 86.90 mg/g. Compared to the traditional materials, the molecularly imprinted chitosan microspheres‐magnetic graphene oxide produced higher selectivity and extraction capacity.  相似文献   

13.
A surface carbamazepine‐imprinted polymer was grafted and synthesized on the SiO2/graphene oxide surface. Firstly SiO2 was coated on synthesized graphene oxide sheet using the sol–gel technique. Prior to polymerization, the vinyl group was incorporated on to the surface of SiO2/graphene oxide to direct selective polymerization on the surface. Methacrylic acid, ethylene glycol dimethacrylate and ethanol were used as monomer, cross‐linker and porogen, respectively. Nonimprinted polymer was also prepared for comparison. The properties of the molecularly imprinted polymer were characterized using field‐emission scanning electron microscopy and Fourier‐transform infrared spectroscopy. The surface molecularly imprinted polymer was utilized as an adsorbent of dispersive solid‐phase extraction for separation and preconcentration of carbamazepine. The effects of the different parameters influencing the extraction efficiency, such as sample pH were investigated and optimized. The specificity of the molecular imprinted polymer over the nonimprinted polymer was examined in absence and presence of competitive drugs. The carbamazepine calibration curve showed linearity in the ranges 0.5–500 μg/L. The limits of detection and quantification under the optimized conditions were 0.1 and 0.3 μg/L, respectively. The within‐day and between‐day relative standard deviations (n = 3) were 3.6 and 4.3%, respectively. Furthermore, the relative recoveries for spiked biological samples were above 85%.  相似文献   

14.
In this study, porous sandwich structure Fe3O4 nanoparticles coated by polyhedral oligomeric silsesquioxanes and β‐cyclodextrin were prepared by surface polymerization and were used as the magnetic solid phase extraction adsorbent for the extraction and determination of carbaryl and carbofuran. The Fe3O4 nanoparticles coated with polyhedral oligomeric silsesquioxanes and β‐cyclodextrin were characterized by Fourier transform infrared spectroscopy, X‐ray diffraction, thermogravimetric analysis, vibrating sample magnetometry, and scanning electron microscopy. After optimizing the extraction conditions, a method that combined magnetic solid phase extraction with high‐performance liquid chromatography was developed for the determination of carbaryl and carbofuran in apple. The method exhibited a good linearity in the range of 2–400 μg/kg for carbaryl and carbofuran (R= 0.9995), respectively. The limits of detection were 0.5 μg/kg of carbaryl and 0.7 μg/kg for carbofuran in apple, respectively. Extraction recoveries ranged from 94.2 to 103.1% with the preconcentration factor of 300 and the relative standard deviations were less than 5.9%. These results indicated that the method combined magnetic solid phase extraction with high‐performance liquid chromatography and was promising for the determination of carbaryl and carbofuran at trace amounts.  相似文献   

15.
Sample pretreatment is essential for the analysis of complicated real samples due to their complex matrices and low analyte concentrations. Among all sample pretreatment methods, solid‐phase extraction is arguably the most frequently used one. However, the majority of available solid‐phase extraction adsorbents suffer from limited selectivity. Molecularly imprinted polymers are a type of tailor‐made artificial antibodies and receptors with specific recognition sites for target molecules. Using molecularly imprinted polymers instead of conventional adsorbents can greatly improve the selectivity of solid‐phase extraction, and therefore molecularly imprinted polymer‐based solid‐phase extraction has been widely applied to separation, clean up and/or preconcentration of target analytes in various kinds of real samples. In this article, after a brief introduction, the recent developments and applications of molecularly imprinted polymer‐based solid‐phase extraction for determination of different analytes in complicated real samples during the 2015‐2020 are reviewed systematically, including the solid‐phase extraction modes, molecularly imprinted adsorbent types and their preparations, and the practical applications of solid‐phase extraction to various real samples (environmental, food, biological, and pharmaceutical samples). Finally, the challenges and opportunities of using molecularly imprinted polymer‐based solid‐phase extraction for real sample analysis are discussed.  相似文献   

16.
Molecularly imprinted polymers were prepared via β‐cyclodextrin‐stabilized oil‐in‐water Pickering emulsion polymerization for selective recognition and adsorption of erythromycin. The synthesized molecularly imprinted polymers were spherical in shape, with diameters ranging from 20 to 40 µm. The molecularly imprinted polymers showed high adsorption capacity (87.08 mg/g) and adsorption isotherm data fitted well with Langmuir model. Adsorption kinetics study demonstrated that the molecularly imprinted polymers acted in a fast adsorption kinetic pattern and the adsorption features of molecularly imprinted polymers followed a pseudo‐first‐order model. Adsorption selectivity analysis revealed that molecularly imprinted polymers had a much better specificity for erythromycin than that for spiramycin or amoxicillin, and the relative selectivity coefficient values on the bases of spiramycin and amoxicillin were 3.97 and 3.86, respectively. The Molecularly imprinted polymers also showed a satisfactory reusability after four times of regeneration. In addition, molecularly imprinted polymers exhibited good adsorption capacities for erythromycin under complicated environment, that is, river water and milk. These results proved that the as‐prepared molecularly imprinted polymers is a potent absorbent for selective recognition of erythromycin, and therefore it may be a promising candidate for practical applications, such as wastewater treatment and detection of erythromycin residues in food.  相似文献   

17.
Molecularly imprinted polymers were synthesized using mixed tea saponins as a template and acrylamide‐β‐cyclodextrin as a cofunctional monomer for the specific binding and purification of tea saponins from the defatted cake extract of Camellia oleifera. The adsorption properties of the prepared polymers were systematically evaluated including adsorption kinetics, adsorption isotherms, and selective recognition characteristics. It showed that the adsorption kinetics followed the pseudo first‐order kinetic model (R2 = 0.995) with an equilibrium time of 3 h, adsorption isotherm data fitted well with the Langmuir–Freundlich model (R2 = 0.984) with an adsorption capacity of 14.23 mg/g. The relative selectivity coefficient (k´) in the presence of the analogues glycyrrhizic acid and glycyrrhetinic acid were 1.16 and 17.21, respectively. The performance of the molecularly imprinted polymers as solid‐phase extraction materials was investigated and the results indicated that using acrylamide‐β‐cyclodextrin as a cofunctional monomer improved both the adsorption capacity and active sites stability of the imprinted polymers. The solid‐phase extraction using the polymers as packing materials was subsequently applied for the separation of tea saponins in raw C. oleifera press extract, and targets were obtained with a purity reaching 89%.  相似文献   

18.
β‐Cyclodextrin and its derivatives can selectively bind to various organic molecules in its cavity and provide good applications in sample preparation. Surface‐enhanced Raman spectroscopy is a sensitive technique and has received increasing attention in the last decade. Herein, 3,5‐dimethyl phenyl carbamoylated β‐cyclodextrin bonded silica gel was used as a ssorbent in solid‐phase extraction to selectively enrich forchlorfenuron and thidiazuron followed by determination with surface‐enhanced Raman spectroscopy. It showed excellent selectivity for forchlorfenuron and thidiazuron and the adsorption capacities were 40.0 and 30.0 μg/g, respectively. A rapid and sensitive method based on the modified β‐cyclodextrin solid‐phase extraction coupled with surface‐enhanced Raman spectroscopy was developed. The linear ranges were 30.0–300.0 μg/L for forchlorfenuron and thidiazuron at 1005 and 640 cm?1, respectively. Both of the limits of detection were 15.0 μg/L, which were significantly lower than the maximum permitted by the National Standard. The recoveries of forchlorfenuron and thidiazuron were 78.9–87.9% for the spiked grape, kiwi, cucumber and tomato, with relative standard deviations of 8.1–13.2%. The results show that this method is sensitive, selective, and relatively time saving, and has great potential in the analysis of trace amounts of plant growth regulators in fruits and vegetables.  相似文献   

19.
A novel multiple‐template surface molecularly imprinted polymer (MTMIP) was synthesized using ofloxacin and 17β‐estradiol as templates and modified monodispersed poly(glycidylmethacrylate‐co‐ethylene dimethacrylate) (PGMA/EDMA) beads as the support material. Static adsorption, solid‐phase extraction and high‐performance liquid chromatography were performed to investigate the adsorption properties and selective recognition characteristics of the polymer templates and their structural analogs. The maximum binding capacities of ofloxacin and 17β‐estradiol on the MTMIP were 9.0 and 6.6 mg/g, respectively. Compared with the corresponding nonimprinted polymer, the MTMIP exhibited a much higher adsorption performance and selectivity toward three quinolones and three estrogens, which are common drug residues in food. The MTMIP served as a simple and effective pretreatment method and could be successfully applied to the simultaneous analysis of multiple target components in complex samples. Furthermore, the MTMIP may find useful applications as a solid‐phase absorbent in the simultaneous determination of trace quinolones and estrogens in milk samples, as the recoveries were in the range 77.6–98.0%. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

20.
Toward improving the selective adsorption performance of molecularly imprinted polymers in strong polar solvents, in this work, a new ionic liquid functional monomer, 1‐butyl‐3‐vinylimidazolium bromide, was used to synthesize sulfamethoxazole imprinted polymer in methanol. The resulting molecularly imprinted polymer was characterized by Fourier transform infrared spectra and scanning electron microscopy, and the rebinding mechanism of the molecularly imprinted polymer for sulfonamides was studied. A static equilibrium experiment revealed that the as‐obtained molecularly imprinted polymer had higher molecular recognition for sulfonamides (e.g., sulfamethoxazole, sulfamonomethoxine, and sulfadiazine) in methanol; however, its adsorption of interferent (e.g., diphenylamine, metronidazole, 2,4‐dichlorophenol, and m‐dihydroxybenzene) was quite low. 1H NMR spectroscopy indicated that the excellent recognition performance of the imprinted polymer was based primarily on hydrogen bond, electrostatic and π‐π interactions. Furthermore, the molecularly imprinted polymer can be employed as a solid phase extraction sorbent to effectively extract sulfamethoxazole from a mixed solution. Combined with high‐performance liquid chromatography analysis, a valid molecularly imprinted polymer‐solid phase extraction protocol was established for extraction and detection of trace sulfamethoxazole in spiked soil and sediment samples, and with a recovery that ranged from 93–107%, and a relative standard deviation of lower than 9.7%.  相似文献   

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