Preparation and Characterization of Metolachlor Molecularly Imprinted Polymer Coating on Stainless Steel Fibers for Solid-Phase Microextraction

A molecularly imprinted polymer (MIP) with metolachlor as the template molecule was first coated on the surface of stainless steel fibers through chemical bonding. Despite 12 times repeated coating procedures, a homogenous, porous, and highly cross-linked MIP coating was obtained with thickness of 17.4 µm (RSD of 6.1%). The specific selectivity of MIP coating to metolachlor and three metabolites could be concluded with 4.4, 4.1, 3.9, and 2.9 times higher extraction amounts of metolachlor, hydroxymetolachlor, deschlorometolachlor, and desmethylmetolachlor than that of the NIP coating, respectively, and good extraction capabilities for chloroacetanilide herbicides were found with the MIP-coated SPME stainless steel fiber. For validation, the fiber was applied for the extraction of metolachlor, propisochlor, and butachlor in spiked corn and soybean samples, and the recoveries of 90.7–92.6%, 86.4–87.9, and 85.4–87.5% were obtained, respectively.     

Preparation of temperature sensitive molecularly imprinted polymer for solid-phase microextraction coatings on stainless steel fiber to measure ofloxacin

A kind of new temperature sensitive molecularly imprinted polymer (MIP) with ofloxacin (OFL) as template was prepared for the coating of solid phase microextraction (SPME). Dopamine was self-polymerized on stainless steel fiber (SSF) as the SPME support followed by silanization. Then MIP was synthesized as SPME coating on the modified SSF in a capillary, with N-isopropyl acrylamide as temperature sensitive monomer and methacrylic acid as functional monomer. The synthesis could be well repeated with multiple capillaries putting in the same reaction solution. The obtained MIP fiber was evaluated in detail with different techniques and various adsorption experiments. At last the MIP fiber was used to extract the OFL in milk. Satisfied recoveries between 89.7 and 103.4% were obtained with the limit of quantification (LOQ_LC) of 0.04 μg mL⁻¹ by the method of SPME coupled with high performance of liquid chromatography (HPLC).     

Preparation and application of solid-phase microextraction fiber based on molecularly imprinted polymer for determination of anabolic steroids in complicated samples

A relatively selective, chemically and physically robust SPME fiber was developed in a simple way with testosterone-imprinted polymer, and then directly coupled with gas chromatography-mass spectrometry (GC-MS) for selective extraction and analysis of anabolic steroids. The factors influencing polymerization (i.e., cross-linker, polymerization solvent, polymerization time) were optimized in detail and the polymer was characterized by scanning electron microscope, infrared spectrometer and thermogravimetric analyzer. Furthermore, the extraction performance of the MIP-coated SPME fibers such as extraction ability and selectivity was evaluated. Moreover, the interaction mode between target analytes and fiber coating was deducted. Finally, the method for extraction and determination of androsterone, stanolone, androstenedione and methyltestosterone by the homemade MIP-coated SPME fibers with GC-MS was obtained. It was applied to the simultaneous analysis of four anabolic steroids in the spiked human urine with the satisfactory recoveries.     

Novel liquid-liquid-solid microextraction method with molecularly imprinted polymer-coated stainless steel fiber for aqueous sample pretreatment

A novel liquid-liquid-solid microextraction (LLSME) method was developed to overcome the well-known water-compatibility problem of molecularly imprinted polymers (MIPs). The enrichment factors with MIP-LLSME method were within 70-210 for trace chloroacetanilide herbicides under optimized extraction conditions. The method was characterized by simplicity, low solvent-consumption and high selectivity, and it was suitable for the one-step pretreatment of various aqueous samples such as river water and farm water.     

A novel molecularly imprinted solid-phase microextraction fiber coupled with high performance liquid chromatography for analysis of trace estrogens in fishery samples

The combination of molecular imprinting and solid-phase microextraction (SPME) technique provides a powerful sample preparation tool in terms of selectivity, simplicity, and flexibility. This paper reports a novel molecularly imprinted polymer (MIP) coated SPME fiber with 17β-estradiol as template by improved multiple co-polymerization method. The obtained fiber exhibits excellent characteristics such as high porosity, good thermal and chemical stability. Extraction performance shows that the MIP-coated fiber has stronger affinity to the template molecule as compared with the commercial SPME fibers and the control polymer-coated fiber without addition of template. Owing to the shape and structural compatibility, the obtained fiber also demonstrated specific selectivity to the structural related compounds of 17β-estradiol, such as estriol, estrone and 17α-ethynylestradiol, and thus can be applied to simultaneous determination of these estrogens from complex samples coupled with high performance liquid chromatography. The variables that influence extraction were investigated. The MIP-coated fiber demonstrated its efficiency for extraction of estrogens in fishery samples. The detection limits were in the range of 0.98-2.39 μg L⁻¹, and the recoveries were 80.0-83.6% and 85.0-94.1% for fish and shrimp tissue samples, respectively.     

Polydopamine supported preparation method for solid-phase microextraction coatings on stainless steel wire

In this paper, we introduced a novel and versatile route to prepare solid-phase microextraction coatings on the chemically inert stainless steel wire. Polydopamine films can be created on metallic substrates by an oxidant-induced polymerization and subsequently support various secondary reactions to prepare functional surfaces. In the present work, polydopamine-bioactivated stainless steel wire was successfully modified by nanostructured hydroxyapatite. Extraction performance of the fiber was assessed on several polycyclic aromatic hydrocarbons in water solutions. Extraction mechanism was suggested based on the correlation of partition coefficients and LogPs. Both aqueous and solid real life samples were used to test the reliability of the solid-phase microextraction-gas chromatography method; some analytes were detected and quantified.     

马拉硫磷分子印迹聚合物的制备及其在固相萃取中的应用

以马拉硫磷为模板分子,采用原位逐步聚合法制备了具有良好识别性能的分子印迹聚合物(MIPs),考察了马拉硫磷、甲基对硫磷、对硫磷及甲胺磷在马拉硫磷聚合物的选择性分离富集特性。用聚合物固相萃取了蜂蜜、蔬菜和天然水中的马拉硫磷。结果表明,聚合物对模板分子产生了印迹效应,对马拉硫磷有明显的选择性。流速为1.0 mL/min,进...     

Evaluation of a new method for chemical coating of aluminum wire with molecularly imprinted polymer layer. Application for the fabrication of triazines selective solid-phase microextraction fiber

A new solid-phase microextraction (SPME) fiber is fabricated through ultra violet irradiation polymerization of ametryn-molecularly imprinted polymer on the surface of anodized-silylated aluminum wire. The prepared fiber is durable with very good chemical and thermal stability which can be coupled to GC and GC/MS. The effective parameters on the fabrication and application procedures such as spraying mode, ultra violet irradiation (polymerization) time, number of sprayings and polymerizations, pH and ionic strength of sample and extraction time were optimized. This fiber shows high selectivity with great extraction capacity toward triazines. SPME and GC analysis of ametryn, prometryn, terbutryn, atrazine, simazine, propazine and cyanazine using the fabricated fiber result in the detection limits of 9, 32, 27, 43, 51, 74 and 85 ng mL⁻¹, respectively. The reliability of the prepared fiber in real samples has been investigated and proved by using spiked tap water, rice, maize and onion samples.     

Development of metal complex imprinted solid-phase microextraction fiber for 2,2'-dipyridine recognition in aqueous medium

In this paper, a novel metal complex imprinted polymer (CIP) coated solid-phase microextraction (SPME) fiber was prepared which could recognize the complex template [Cu(OAc)₂(2,2′-dipyridine)] in aqueous medium. The saturating adsorption capacity of CIP-coated fiber was 2.2 and 2.6 times greater than those of molecularly imprinted polymer (MIP) coated fiber and nonimprinted polymer (NIP) coated fiber, respectively. Extraction conditions that influenced the recognition performance of CIP-coated fiber were investigated including pH, extraction solvent, metal ion species, etc. The ligand selectivity was also evaluated and discussed. The results demonstrated that CIP-coated fiber had better binding affinity for 2,2′-dipyridine compared to its structure analogues. The recognition ability of CIP coating was stable and effective in aqueous medium while MIP coating showed weak imprinting effect due to disturbance from protic solvent. 2,2′-dipyridine extracted by CIP-coated fiber using HPLC/UV detection resulted in a linear range of 10-200 μg/L with a detection limit of 2.0 μg/L. The proposed method was successfully applied to the analysis of 2,2′-dipyridine in spiked tap water, laboratory wastewater and human urine samples with recoveries 80.3-103.3% and RSDs 5.5-8.9%.     

Synthesis and application of a molecularly imprinted polymer in the solid-phase extraction of ketoprofen from wastewater

Ketoprofen is a nonsteroidal anti-inflammatory drug widely consumed by humans as it possesses analgesic activities. A selective molecularly imprinted polymer (MIP) for ketoprofen was synthesized and applied as a solid-phase extraction sorbent. MIP was synthesized using 2-vinylpyridine, ethylene glycol dimethacrylate, 1,1′-azobis(cyclohexanecarbonitrile), toluene/acetonitrile (9:1, v/v), and ketoprofen as a functional monomer, cross-linker, initiator, porogenic mixture, and template, respectively. The polymerization was performed at 60 °C for 16 h, and thereafter the temperature was increased to 80 °C for 24 h to achieve a solid monolith polymer. Nonimprinted polymer was synthesized in a similar manner with the omission of ketoprofen. Characterization with thermogravimetric analysis and X-ray diffraction showed that the synthesized polymers were thermally stable and amorphous. Solid-phase extraction cartridges packed with MIP were used with high-performance liquid chromatography for quantitative analysis of ketoprofen in wastewater. The analytical method gave detection limits of 0.23, 0.17, and 0.09 μg/L in wastewater influent, effluent, and deionized water, respectively. The recovery for the wastewater influent and effluent spiked with 5 μg/L of ketoprofen was 68%, whereas 114% was obtained for deionized water. The concentrations of ketoprofen in the influent and effluent samples were in the ranges of 22.5–34.0 and 1.14–5.33 μg/L, respectively. Overall, the analytical method for the analysis of ketoprofen in wastewater was rapid, affordable, accurate, precise, sensitive, and selective.     

A simple approach for the preparation of simazine molecularly imprinted nanofibers via self-polycondensation for selective solid-phase microextraction

A novel molecularly imprinted sol-gel material based on polysiloxane nanofiber was introduced as a solid-phase microextraction coating on a stainless steel wire for the extraction of simazine. The nanostructured molecularly imprinted fiber was prepared by a simple single step method at room temperature, using methyltriethoxysilane as the sol-gel precursor and simazine as the template molecule. The fiber was applied for the extraction of simazine in different water samples followed by gas chromatography and mass spectrometry detection. The extraction capacity of the molecularly imprinted fiber was 8 ng, and it had better extraction efficiency than the non-imprinted fiber and commercial fibers (PDMS and PA). The fiber had also a good selectivity for simazine and its analogous compounds. Important parameters affecting the extraction and desorption efficiency, such as salt concentration, stirring rate, pH of sample solution, extraction time and temperature, temperature and time of desorption, were investigated. The intra- and inter-day relative standard deviations were in the range of 4.3–7.6%. The fiber-to-fiber reproducibility was 7.7–8.5%. The method showed a good linearity (r²> 0.9980) in the range of 0.02–20 μg L⁻¹ with the detection limit of 0.005 μg L⁻¹. The relative recoveries were also in the range of 94–97% for different water samples.     

Preparation and binding study of solid-phase microextraction fiber on the basis of ametryn-imprinted polymer: Application to the selective extraction of persistent triazine herbicides in tap water,rice, maize and onion

A monolithic ametryn molecular-imprinted polymer based on a simple polymerization method was fabricated for use as new solid-phase microextraction (SPME) fiber, which can be coupled with GC and GC/MS for selective extraction and analysis of triazine herbicides. Methacrylic acid (MAA), ethylene glycol dimethacrylate (EDMA) and ametryn bear role of functional monomer, cross-linker and template, respectively. In the optimized conditions the fabricated fiber showed better molecular recognition abilities for methylthiotriazine herbicides than chloro-triazine herbicides. By use of bi-Langmuir isotherm model the evaluated equilibrium constants for ametryn were 0.01 and 890.69 μM⁻¹, and the numbers of binding sites were 129.98 and 5.82 nmol g⁻¹, respectively. The high extraction efficiency was obtained for ametryn, prometryn, terbutryn, atrazine, simazine, propazine, and cyanazine, yielding the detection limits of 14, 28, 45, 56, 85, 95 and 74 ng mL⁻¹, respectively by GC with flame ionization detection. The reliability of the prepared fiber for extraction of ametryn and other analogues in real samples has been investigated and proved by using spiked samples such as tap water, rice, maize, and onion.     

Preparation and evaluation of molecularly imprinted solid-phase microextraction fibers for selective extraction of bisphenol A in complex samples

Molecular imprinted polymer (MIP) as solid-phase microextraction (SPME) fibers coating has gained great attention in recent years. In this study, a simple preparation approach for bisphenol A (BPA) MIP coating with controlled thickness on fused-silica capillaries was developed. A capillary was inserted into a larger bore capillary to form a sleeve as mold. The prepolymer solution containing the template BPA was introduced into the interspace between the two capillaries for polymerization under photoirradiation. The larger bore capillary was removed away after the polymerization, and MIP coating with certain thickness on the surface of the inserted capillary was obtained. SPME conditions based on the MIP-coated fibers were optimized, and the extraction performance of the fibers with different thickness coating was compared. Finally, the MIP fibers were used for selective extraction of BPA spiked in tap water, human urine, and milk samples. The average recoveries of spiked BPA in the three samples were 92.5%, 81.6%, and 87.5%, respectively. The present analytical performance is not up to par for applicability to real environmental matrices. Further improvement will be necessary for analysis of real complex samples.     

Molecularly imprinted solid-phase extraction for the selective determination of bromhexine in human serum and urine with high performance liquid chromatography

In this work, a novel method is described for the determination of bromhexine in biological fluids using molecularly imprinted solid-phase extraction as the sample cleanup technique combined with high performance liquid chromatography (HPLC). The water-compatible molecularly imprinted polymers (MIPs) were prepared using methacrylic acid as functional monomer, ethylene glycol dimethacrylate as cross-linker, chloroform as porogen and bromhexine as the template molecule. The novel imprinted polymer was used as a solid-phase extraction sorbent for the extraction of bromhexine from human serum and urine. Various parameters affecting the extraction efficiency of the polymer have been evaluated. The optimal conditions for molecularly imprinted solid-phase extraction (MISPE) consisted of conditioning 1 mL methanol and 1 mL of deionized water at neutral pH, loading of 5 mL of the water sample (25 μg L⁻¹) at pH 6.0, washing using 2 mL acetonitrile/acetone (1/4, v/v) and elution with 3× 1 mL methanol/acetic acid (10/1, v/v). The MIP selectivity was evaluated by checking several substances with similar molecular structures to that of bromhexine. Results from the HPLC analyses showed that the calibration curve of bromhexine using MIP from human serum and urine is linear in the ranges of 0.5-100 and 1.5-100 μg L⁻¹ with good precisions (3.3% and 2.8% for 5.0 μg L⁻¹), respectively. The recoveries for serum and urine samples were higher than 92%.     

Growth of cedar-like Au nanoparticles coating on an etched stainless steel wire and its application for selective solid-phase microextraction

A novel cedar-like Au nanoparticles (AuNPs) coating was fabricated on an etched stainless steel (SS) wire by direct chemical deposition and used as an efficient and unbreakable solid phase microextraction (SPME) fiber. The etched SS wire offers a rough surface structure for subsequent growth of AuNPs in chloroauric acid solution. As a result, the uniform cedar-like AuNPs coating with larger surface area was tightly attached to the etched SS wire substrate. The AuNPs coated etched SS fiber (AuNPs/SS) was examined for SPME of ultraviolet (UV) filters, phthalate esters and aromatic hydrocarbons coupled to high-performance liquid chromatography with UV detection. The fabricated fiber exclusively exhibited excellent extraction efficiency and selectivity for some aromatic hydrocarbons. Influential parameters of extraction and desorption time, temperature, stirring rate and ionic strength were investigated and optimized. The limits of detection ranged from 0.008 μg L⁻¹ to 0.037 μg L⁻¹. The single fiber repeatability varied from 3.90% to 4.50% and the fiber-to-fiber reproducibility ranged from 5.15% to 6.87%. The recovery of aromatic hydrocarbons in real water samples spiked at 2.0 μg L⁻¹ and 20 μg L⁻¹ ranged from 94.38% to 106.2% with the relative standard deviations below 6.44%. Furthermore the growth of the cedar-like AuNPs coating can be performed in a highly reproducible manner. This fabricated fiber exhibits good stability and withstands at least 200 extraction and desorption replicates.     

Molecularly imprinted solid-phase extraction of cocaine metabolites from aqueous samples

Cocaine is a well-known drug of abuse which, when ingested nasally or by smoking, undergoes a number of biotransformation and degradation reactions. In the present work, a synthetic analogue of the cocaine metabolite benzoylecgonine was prepared and used as a template molecule in the preparation of a series of molecularly imprinted polymers (MIPs). Molecularly imprinted solid-phase extraction (MISPE) conditions were established under which benzoylecgonine in aqueous samples could be selectively extracted and quantified at clinically relevant concentrations (μg/ml). Under optimised MISPE conditions, recoveries of analyte were high (>70%) and excellent discrimination between imprinted and non-imprinted materials observed.     

A novel method to prepare monolithic molecular imprinted polymer fiber for solid‐phase microextraction by microwave irradiation†

In this paper, a new approach to prepare monolithic molecularly imprinted polymer (MIP) fibers for solid‐phase microextraction is proposed with the help of microwave irradiation. Imprinting polymerization was carried out within silica capillaries in 4.5 min, using dimethyl phthalate (DMP) as a template molecular, α‐methacrylic acid as a functional monomer and ethylene dimethacrylate as a crosslinker, acetonitrile as the porogenic solvent. The synthesis was optimized by varying the ratio of template/monomer and different volume of porogen. The resulted MIP fibers were obtained after silica being etched away with a controlled length of 1 cm, and subsequently characterized by SEM. In order to increase the selective extraction of DMP, factors affecting the extraction including extraction time, salt concentration, desorption time, and desorption solvents were investigated for solid‐phase microextraction procedures in detail. The selectivity coefficients, defined as the extraction amount ratio of MIP to its nonimprinting fiber, were 5.6, 2.6, and 1.4 for DMP and its counterpart including dibutyl phthalate and di‐n‐octylo‐phthalate, respectively. The resulted fibers were also applied to detect DMP, dibutyl phthalate, and di‐n‐octylo‐phthalate in bottled beverage samples coupled to HPLC and resulted in relative recoveries of up to 73.8–98.5%, respectively.     

分子印迹在线富集-化学发光法测定葡萄酒和虎杖提取物中的白藜芦醇

制备了白藜芦醇的分子印迹聚合物,用聚四氟乙烯管作为微固相萃取柱,连接在流动注射系统的八通阀上,对白藜芦醇进行富集和分离;经甲醇和乙酸混合洗脱液(9:1,V/V)在线洗脱后与酸性KMnO4发生化学发光反应.测定白藜芦醇的线性范围2.5×10-7～6.1×10-5g/mL,方法的检出限为(3σ)8×10-8g/mL,11次...     

Molecularly imprinted solid-phase extraction and flow-injection chemiluminescence for trace analysis of 2,4-dichlorophenol in water samples

Highly sensitive flow-injection chemiluminescence (CL) combined with molecularly imprinted solid-phase extraction (MISPE) has been used for determination of 2,4-dichlorophenol (2,4-DCP) in water samples. The molecularly imprinted polymer (MIP) for 2,4-DCP was prepared by non-covalent molecular imprinting methods, using 4-vinylpyridine (4-VP) and ethylene glycol dimethacrylate (EGDMA) as the monomer and cross-linker, respectively. 2,4-DCP could be selectively adsorbed by the MIP and the adsorbed 2,4-DCP was determined by its enhancing effect on the weak chemiluminescence reaction between potassium permanganate and luminol. The enhanced CL intensity was linear in the range from 1 × 10⁻⁷ to 2 × 10⁻⁵g mL⁻¹. The LOD (S/N = 3) was 1.8 × 10⁻⁸g mL⁻¹, and the relative standard deviation (RSD) was 3.0% (n = 11) for 1.4 × 10⁻⁶g mL⁻¹. The proposed method had been successfully applied to the determination of 2,4-DCP in river water. Figure Effect of 4-VP content on the ultraviolet spectrum of 2,4-DCP in chloroform     

Preparation, evaluation and application of molecularly imprinted solid-phase microextraction monolith for selective extraction of pirimicarb in tomato and pear

A simple, rapid and sensitive method for the determination of pirimicarb in tomato and pear using polymer monolith microextraction (PMME) based on the molecularly imprinted polymer (MIP) monolith combined with high-performance liquid chromatography-photodiodes array detector (HPLC-PAD) was developed. By optimizing the polymerization conditions, such as the nature of porogenic solvent and functional monomer, the molar ratio of the monomer and cross-linker, an pirimicarb MIP monolith was synthesized in a micropipette tip using methacrylic acid (MAA) as the functional monomer, ethylene dimethacrylate (EGDMA) as the cross-linker and the mixture of toluene-dodecanol as the porogenic solvent. The MIP monolith showed highly specific recognition for the template pirimicarb. The monolith was applied for the selective extraction of pirimicarb in tomato and pear. Several parameters affecting MIP-PMME were investigated, including the nature and volume of extraction solvent, sample volume, flow rate and sample pH. Under the optimum PMME and HPLC conditions, the linear ranges were 2.0-1400 μg/kg for pirimicarb in tomato and pear with the correlation coefficient of above 0.999. The detection limits (s/n=3) were both 0.6 μg/kg. The proposed method was successfully applied for the selective extraction and determination of pirimicarb in tomato and pear.