Separation and determination of ciprofloxacin in seawater,human blood plasma and tablet samples using molecularly imprinted polymer pipette‐tip solid phase extraction and its optimization by response surface methodology

By synthesizing a molecular imprinted polymer as an efficient adsorbent, ciprofloxacin was micro‐extracted from seawater, human blood plasma and tablet samples by pipette‐tip micro solid phase extraction and determined spectrophotometrically. Response surface methodology was applied with central composite design to build a model based on factors affecting on microextraction of ciprofloxacin; including volume of eluent solvent, number of extraction cycles, number of elution cycles, and pH of sample. Other factors that affect extraction efficiency, such as type of eluent solvent, volume of sample, type, and amount of salt were optimized with one‐variable‐at‐a‐time method. Under optimum extraction condition, pH of sample solution was 7.0, volume of eluent solvent (methanol) was 200 µL, volume of sample solution was 10 mL, and the number of extraction and elution cycles was five and seven, respectively, amount of Na₂SO₄ (as salt) and MIP (as sorbent) were optimized at 150 and 2 mg, respectively. The linear range of the suggested method under optimum extraction factors was 5–150 µg/L with a limit of detection of 1.50 µg/L for the analyte. Reproducibility of the method (as relative standard deviation) was better than 7%.     

A novel molecularly imprinted polymer for simultaneous extraction and determination of sudan dyes by on-line solid phase extraction and high performance liquid chromatography

A novel molecularly imprinted polymer was synthesized with attapulgite employed as matrix, which is simple and time-saving. In this method, sudan I was chosen as template molecule, 2-vinylpyridine as functional monomer and ethylene glycol dimethacrylate as cross-linking agent, respectively. The imprinted polymer was characterized by the infrared spectroscopy and transmission electron microscopy. Then the selectivity experiments were performed on sudan dyes and the recognition coefficients for sudan I, sudan II, sudan III and sudan IV were 2.9, 1.9, 1.9 and 2.3, respectively. As the packing material of solid-phase extraction, the imprinted polymer has been applied to on-line concentration of the four sudan dyes in samples from Yellow River water, tomato sauce and sausage. The corresponding analytical methods to determine these sudan dyes have been developed. The limits of detection for these sudan dyes were in the range of 0.01–0.05 ng mL⁻¹ for Yellow River water, 1.0–3.0 ng g⁻¹ for tomato sauce and 0.8–3.0 ng g⁻¹ for sausage.     

A molecularly imprinted polymer for solid phase extraction of allantoin

We describe a molecularly imprinted polymer (MIP) for the solid-phase extraction of the skin protectant allantoin. The MIP was deposited on the surface of monodisperse silica microspheres possessing acroyl groups on the surface (MH-SiO₂). The resulting MIP microspheres (MH-SiO₂@MIP) showed a 3.4-fold higher adsorption capacity and a 1.9-fold better selectivity for allantoin than the respective non-imprinted polymer (MH-SiO₂@NIP). The monolayer adsorption capacities of the MH-SiO₂@MIP and the MH-SiO₂@NIP were calculated with the help of the Langmuir model and found to be 6.8 and 1.9 mg?g^?1, respectively. Adsorption kinetics fit a pseudo-second order rate mechanism, with an initial adsorption rate of 1.44 for the MH-SiO₂@MIP, and of 0.07 mg?g^?1?min^?1 for the MH-SiO₂@NIP. The material can be regenerated, and its adsorption capacity for allantoin remains stable for at least five regeneration cycles. It was successfully used as a sorbent for the selective solid-phase extraction of allantoin from Rhizoma dioscoreae.

A molecularly imprinted polymer for solid phase extraction of allantoin

We describe a molecularly imprinted polymer (MIP) for the solid-phase extraction of the skin protectant allantoin. The MIP was deposited on the surface of monodisperse silica microspheres possessing acroyl groups on the surface (MH-SiO₂). The resulting MIP microspheres (MH-SiO₂@MIP) showed a 3.4-fold higher adsorption capacity and a 1.9-fold better selectivity for allantoin than the respective non-imprinted polymer (MH-SiO₂@NIP). The monolayer adsorption capacities of the MH-SiO₂@MIP and the MH-SiO₂@NIP were calculated with the help of the Langmuir model and found to be 6.8 and 1.9 mg•g⁻¹, respectively. Adsorption kinetics fit a pseudo-second order rate mechanism, with an initial adsorption rate of 1.44 for the MH-SiO₂@MIP, and of 0.07 mg•g⁻¹•min⁻¹ for the MH-SiO₂@NIP. The material can be regenerated, and its adsorption capacity for allantoin remains stable for at least five regeneration cycles. It was successfully used as a sorbent for the selective solid-phase extraction of allantoin from Rhizoma dioscoreae.

A molecularly imprinted polymer for the selective separation of allantoin was developed. It was successfully used as a sorbent for the selective solid-phase extraction of allantoin from Rhizoma dioscoreae.

     

Synthesis of surface molecularly imprinted polymer and the selective solid phase extraction of imidazole from its structural analogs

A surface molecularly imprinted polymer (MIP) was synthesized by using imidazole as the template and modified silica particles as the support material. The static adsorption, solid phase extraction (SPE) and high-performance liquid chromatography (HPLC) experiments were performed to investigate the adsorption properties and selective recognition characteristics of the polymer for imidazole and its structural analogs. It was shown that the maximum binding capacities of imidazole on the MIP and the non-imprinted polymer (NIP) were 312 and 169 μmol g⁻¹, respectively. The adsorption was fast and the adsorption equilibrium was achieved in 30 min. The binding process could be described by pseudo-second order kinetics. Compared with the corresponding non-imprinted polymer, the molecularly imprinted polymer exhibited much higher adsorption performance and selectivity for imidazole. The selective separation of imidazole from a mixture of 1-hexyl-3-methylimidazolium bromide ([C₆mim][Br]) and 2,4-dichlorophenol could be achieved on the MIP-SPE column. The recoveries of imidazole and [C₆mim][Br] were 97.6-102.7% and 12.2-17.3%, respectively, but 2,4-dichlorophenol could not be retained on the column. The surface molecularly imprinted polymer presented here may find useful application as a solid phase absorbent to separate trace imidazole in environmental water samples. This may also form the basis for our research program on the preparation and application of alkyl-imidazolium imprinted polymers.     

Magnetic molecularly imprinted polymer nanoparticles for the solid-phase extraction of paracetamol from plasma samples,followed its determination by HPLC

We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamol. The m-MIPs were prepared from magnetite (Fe₃O₄) as the magnetic component, paracetamol as the template, methacrylic acid as a functional monomer, and 2-(methacrylamido) ethyl methacrylate as a cross-linker. The m-MIPs were then characterized by transmission electron microscopy, FT-IR spectroscopy, X-ray diffraction and vibrating sample magnetometry. The m-MIPs were applied to the extraction of paracetamol from human blood plasma samples. Following its elution from the column loaded with the m-MIPs with an acetonitrile-buffer (9:1) mixture, it was submitted to HPLC analysis. Paracetamol can be quantified by this method in the 1 μg L^?1 to 300 μg L^?1 concentration range. The limit of detection and limit of quantification in plasma samples are 0.17 and 0.4 μg L^?1. The preconcentration factor of the m-MIPs is 40. The HPLC method shows good precision (4.5 % at 50 μg L^?1 levels) and recoveries (between 83 and 91 %) from spiked plasma samples. Figure

We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamol. The m-MIPs were applied to the extraction of paracetamol from human blood plasma samples     

Magnetic molecularly imprinted polymer nanoparticles for the solid-phase extraction of paracetamol from plasma samples,followed its determination by HPLC

We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamol. The m-MIPs were prepared from magnetite (Fe₃O₄) as the magnetic component, paracetamol as the template, methacrylic acid as a functional monomer, and 2-(methacrylamido) ethyl methacrylate as a cross-linker. The m-MIPs were then characterized by transmission electron microscopy, FT-IR spectroscopy, X-ray diffraction and vibrating sample magnetometry. The m-MIPs were applied to the extraction of paracetamol from human blood plasma samples. Following its elution from the column loaded with the m-MIPs with an acetonitrile-buffer (9:1) mixture, it was submitted to HPLC analysis. Paracetamol can be quantified by this method in the 1 μg L⁻¹ to 300 μg L⁻¹ concentration range. The limit of detection and limit of quantification in plasma samples are 0.17 and 0.4 μg L⁻¹. The preconcentration factor of the m-MIPs is 40. The HPLC method shows good precision (4.5 % at 50 μg L⁻¹ levels) and recoveries (between 83 and 91 %) from spiked plasma samples.

We are presenting magnetic molecularly imprinted polymer nanoparticles (m-MIPs) for solid-phase extraction and sample clean-up of paracetamol. The m-MIPs were applied to the extraction of paracetamol from human blood plasma samples

     

Magnetic molecularly imprinted specific solid‐phase extraction for determination of dihydroquercetin from Larix griffithiana using HPLC

The naturally occurring quercetin flavonoid, dihydroquercetin, is widely distributed in plant tissues and has a variety of biological activities. Herein, a magnetic molecularly imprinted solid‐phase extraction was tailor made for selective determination of dihydroquercetin in Larix griffithiana using high‐performance liquid chromatography. Amino‐functionalized core‐shell magnetic nanoparticles were prepared and characterized using scanning electron microscopy, transmission electron microscopy, vibrating sample magnetometry, and infrared spectroscopy. The polymer had an average diameter of 250 ± 2.56 nm and exhibited good stability and adsorption for template molecule, which is enriched by hydrogen bonding interaction. Multiple factors for extraction, including loading, washing, elution solvents, and extraction time, were optimized. The limit of detection was 1.23 μg/g. The precision determined at various concentration of dihydroquercetin was less than 4% and the mean recovery was between 74.64 and 101.80%. It has therefore been shown that this protocol can be used as an alternative extraction to quantify dihydroquercetin in L. griffithiana and purify quercetin flavonoid from other complex matrices.     

Development of a highly sensitive and selective hyphenated technique (molecularly imprinted micro-solid phase extraction fiber-molecularly imprinted polymer fiber sensor) for ultratrace analysis of folic acid

A simple polymerization strategy is reported in this work which allows molecularly imprinted polymeric fiber (monolith) fabrication for direct use in sensing devices. This is advantageous for achieving higher degree of enrichment of target analyte (folic acid) from the complex matrices of real samples, without any surface fouling, cross-reactivity, and non-specific (false-positive) contributions. In order to measure serum folic acid at ultratrace level to detect spina bifida, a neural tube defect in mother, and other acute cases of proteomic diseases, the hyphenation between molecularly imprinted micro-solid phase extraction fiber and a complementary molecularly imprinted polymer-carbon composite fiber sensor has been found quite efficient. The primitive diagnosis of many chronic diseases is feasible by estimating folic acid as biomarker, with the detection limit as low as 0.0036 ng mL⁻¹ (relative standard deviation = 0.13%, signal/noise = 3) in human blood serum.     

Application of molecularly imprinted polymer solid-phase extraction for salivary cotinine

A method constituted by molecularly imprinted solid-phase extraction (MISPE) with high-performance liquid chromatography coupled to diode array detector (HPLC-DAD) was developed for cotinine analysis in saliva samples. For this purpose, the separation was carried out with a C18 reversed-phase column at 20 °C. The mobile phase which was composed of a mixture of 09:91 (v/v) acetonitrile/phosphate buffer, pH 6.3, was delivered with isocratic flow rate at 1.4 mL min⁻¹. Employing MISPE, the best conditions were achieved with 1.5 mL of saliva plus 1.5 mL of 0.1 mol L⁻¹ of acetate buffer, pH 5.5, which were then passed through a cartridge previously conditioned with 2 mL acetonitrile, 2 mL methanol, and 2 mL of 0.1 mol L⁻¹ sodium acetate buffer, pH 5.5. The washing was carried out with 1 mL deionized water, 1 mL of 0.1 mol L⁻¹ sodium hydroxide, and 1 mL hexane; finally; the cotinine elution was carried out with 3 mL methanol/water (97.5: 2.5, v/v). Linearity ranged from 30 to 500 ng mL⁻¹ with r > 0.99. Intra-assay, interassay precision, and accuracy ranged from 3.1% to 10.1%, 5.2% to 15.9%, and 99.22% to 111.17%, respectively. The detection and quantification limits were 10 and 30 ng mL⁻¹, respectively. This investigation has provided a reliable method for routine cotinine determination in saliva, and it is an important tool for monitoring cigarette smoke exposure in smokers. The method was applied in five smokers’ samples who consumed around five to 20 cigarettes per day and the values of cotinine in saliva were from 66.7 to 316.16 ng mL⁻¹.     

Solid-phase extraction using a molecularly imprinted polymer for the selective purification and preconcentration of norfloxacin from seawater

Abstract

A highly selective and effective method for the purification and preconcentration of norfloxacin (NFX) in seawater samples was developed based on molecularly imprinted solid-phase extraction (MISPE). The molecularly imprinted polymer was synthesized by precipitation polymerization. Methacrylic acid (MAA) and ethylene glycol dimethacrylate (EGDMA) were used as the functional monomer and crosslinker, respectively. The resulting molecularly imprinted polymer (MIP) showed high adsorption for NFX and was selective for its solid-phase extraction. An offline MISPE method followed by high performance liquid chromatography with diode array detection was established for the determination of NFX in seawater. The recoveries of spiked seawater samples using the MISPE columns were satisfactorily higher than 77.6%. The relative standard deviation was less than 5.60%, and the limit of detection was 0.027?μg L^?1. Four seawater samples obtained from the Bohai Sea were analyzed, and NFX was found only at one location at a concentration of 0.280?μg L^?1.     

Preparation of magnetic molecularly imprinted polymer based on multiwalled carbon nanotubes for selective dispersive micro-solid phase extraction of fenitrothion followed by ion mobility spectrometry analysis

A novel molecularly imprinted polymer based on magnetic multiwalled carbon nanotubes was fabricated and applied for selective dispersive micro-solid phase extraction of fenitrothion prior its determination by ion mobility spectrometry. The composite was synthesized using magnetic multiwalled carbon nanotubes as the support. Methacrylic acid was used as the functional monomer, fenitrothion as the template, ethylene glycol dimethacrylate as the cross-linker, and 2,2-azoisobutyronitrile as the initiator. The resultant polymer was characterized by FTIR spectroscopy, X-ray diffraction, field emission scanning electron microscopy, Brunauer–Emmet–Teller analysis, thermogravimetric analysis, and vibrating sample magnetometer techniques. Experimental factors affecting the extraction efficiency such as pH and amount of sorbent were evaluated. Under optimum experimental conditions, the developed method displayed the linear range of 5–220 μg/L with a detection limit of 1.3 μg/L. The intra- and interday relative standard deviations for determination of fenitrothion were 3.6 and 4.7% (n = 6), respectively. Ultimately, the proposed method was used to monitor trace amounts of fenitrothion in fruits, vegetables, and water samples.     

Isolation and determination of estrogens in water samples by solid‐phase extraction using molecularly imprinted polymers and HPLC

Advanced SPE with molecularly imprinted polymers (MIP) was used in this study. A noncovalent imprinting approach was applied to separate 17β‐estradiol, estriol, and estrone from water samples. Polymer material was prepared by bulk polymerization with methacrylic acid as a functional monomer, divinylbenzene and ethyleneglycol dimethacrylate as crosslinkers, and acetonitrile, acetonitrile/toluene (3:1, v/v) or isooctane/toluene (1:99, v/v) as a porogen. We also prepared an MIP film on a silica gel surface with methacrylic acid and ethyleneglycol dimethacrylate as monomers and acetonitrile as a solvent. Qualitative and quantitative hormone analyses were carried out by HPLC with various detection techniques, including UV/visible spectroscopic detection (diode array detection) and electrochemical detection (CoulArray). The results of the study indicate that MIP technology is an excellent method for the quality control of estrogens in environmental analyses with a low quantification limit for 17β‐estradiol of around 26 (diode array detection) and 0.25 ng/mL (electrochemical detection). The proposed method was found to be suitable for routine determinations of the analyzed compound in environmental laboratories.     

Predicting the performance of molecularly imprinted polymers: Selective extraction of caffeine by molecularly imprinted solid phase extraction

A rational design approach was taken to the planning and synthesis of a molecularly imprinted polymer capable of extracting caffeine (the template molecule) from a standard solution of caffeine and further from a food sample containing caffeine. Data from NMR titration experiments in conjunction with a molecular modelling approach was used in predicting the relative ratios of template to functional monomer and furthermore determined both the choice of solvent (porogen) and the amount used for the study. In addition the molecular modelling program yielded information regarding the thermodynamic stability of the pre-polymerisation complex. Post-polymerisation analysis of the polymer itself by analysis of the pore size distribution by BET yielded significant information regarding the nature of the size and distribution of the pores within the polymer matrix. Here is proposed a stepwise procedure for the development and testing of a molecularly imprinted polymer using a well-studied compound—caffeine as a model system. It is shown that both the physical characteristics of a molecularly imprinted polymer (MIP) and the analysis of the pre-polymerisation complex can yield vital information, which can predict how well a given MIP will perform.     

橄榄醇分子印迹聚合物的制备及评价(英文)

以橄榄醇为模板分子,α-甲基丙烯酸(MAA)为功能单体,乙二醇二甲基丙烯酸酯(EDMA)为交联剂,甲苯和十二醇为溶剂,通过本体聚合法制备了橄榄醇分子印迹聚合物。利用平衡结合实验、扫描电镜(SEM)及红外光谱(FTIR)对分子印迹聚合物(MIP)进行了表征,并用该聚合物进行了加标麦麸中橄榄醇的固相萃取(SPE)研究。平衡结合实验表明MIP对模板分子具有更好的识别性。Scatchard分析表明对橄榄醇分子的吸附存在2类不同结合位点,其中高亲和力结合位点和低亲和力结合位点的解离常数分别为0.021和1.002 mmol/L,相应的最大表观结合量分别为18.74和135.9 μmol/g。在优化的固相萃取条件下,MIP固相萃取柱对加标麦麸中橄榄醇的回收率达到97.8%~98.8%,相对标准偏差为2.8%~4.2%(n=5),线性范围为0.1~100 mg/L,检出限(S/N=3)为0.062 mg/L。与非印迹聚合物(NIP)柱及市售聚苯乙烯/二乙烯基苯(PLS)柱相比,MIP柱的选择性更强,回收率更高,纯化效果更好。     

分子印迹固相萃取技术在天然产物有效成分分离分析中的应用进展

天然产物体系复杂,尤其是一些活性成分含量较低,采用一般的方法对其进行分离富集难度较大。分子印迹聚合物具有良好的亲和性和专一的选择性,将分子印迹固相萃取技术应用于天然药物资源样品前处理过程,能够选择性地分离富集复杂基质中的目标成分。本文对近几年分子印迹固相萃取技术在天然产物有效成分分离分析中的应用进行了总结,分析物包括黄酮类、多元酚类、生物碱类、有机酸类、苯丙素类、萜类以及其他一些类型的生物活性成分。     

Response surface methodology approach for the preparation of a molecularly imprinted polymer for solid‐phase extraction of fenoxycarb pesticide in mussels

The aim of this work was to develop an efficient method for the selective extraction and analysis of fenoxycarb, a carbamate pesticide, in mussel samples using a molecularly imprinted solid‐phase extraction device. The optimization of molecularly imprinted polymer synthesis was performed using the experimental design under the response surface methodology approach. A fast rebinding study and Freundlich isotherm adsorption were carried out to calculate binding capacity B, site number n, and affinity constant K_f. The optimum molecularly imprinted polymer was successfully used as sorbent of a solid‐phase extraction cartridge for the determination of fenoxycarb in real mussel samples. The range of linearity was 0.3–30 mg/L with a correlation coefficient of 0.991. The limit of detection was 0.247 mg/kg. The recovery of fenoxycarb extracted from mussel samples of Mediterranean sea was 97% (n = 3) with relative standard deviation between 6 and 7% proving the reliability of the developed method.     

On-line ionic imprinted polymer selective solid-phase extraction of nickel and lead from seawater and their determination by inductively coupled plasma-optical emission spectrometry

Nickel(II) and lead(II) ionic imprinted 8-hydroxyquinoline polymers were synthesized by a precipitation polymerization technique and were used as selective solid phase extraction supports for the determination of nickel and lead in seawater by flow injection solid phase extraction on-line inductively coupled plasma-optical emission spectrometry. An optimum loading flow rate of 2.25 mL min⁻¹ for 2 min and an elution flow rate of 2.25 mL min⁻¹ for 1 min gave an enrichment factor of 15 for nickel. However, a low dynamic capacity and/or rate for adsorption and desorption was found for lead ionic imprinted polymer and a flow rate of 3.00 mL min⁻¹ for 4-min loading and a flow rate of 2.25 mL min⁻¹ for 1-min elution gave a enrichment factor of 5. The limit of detection was 0.33 μg L⁻¹ for nickel and 1.88 μg L⁻¹ for lead, with a precision (n = 11) of 8% (2.37 μg Ni L⁻¹) for nickel and 11% (8.38 μg Pb L⁻¹) for lead. Accuracy was also assessed by analyzing SLEW-3 (estuarine water) and TM-24 (lake water) certified reference materials, and the values determined were in good agreement with the certified concentrations.     

Preparation and utilization of a molecularly imprinted polymer for solid phase extraction of tramadol

In this paper, a highly selective molecularly imprinted polymer (MIP) for tramadol hydrochloride, a drug used to treat moderate to severe pain, was prepared and its use as solid-phase extraction (SPE) sorbent was demonstrated. The molecularly imprinted solid-phase extraction procedure followed by high performance liquid chromatography with ultraviolet detector (MISPE-HPLC) was developed for selective extraction and determination of tramadol in human plasma and urine. The optimal conditions for molecularly imprinted solid-phase extraction (MISPE) consisted of conditioning with 1 mL methanol and 1 mL of deionized water at neutral pH, loading of tramadol sample (50 μg L⁻¹) at pH 7.5, washing using 1 mL acetone and elution with 3 × 1 mL of 10% (v/v) acetic acid in methanol. The MIP selectivity was evaluated by checking several substances with similar molecular structures to that of tramadol. Results from the HPLC analyses showed that the calibration curve of tramadol (using MIP from human plasma and urine) is linear in the ranges of 6–100 and 3–120 μg L⁻¹ with good precisions (1.9% and 2.9% for 5.0 μg L⁻¹), respectively. The recoveries for plasma and urine samples were higher than 81%.      

Separation and determination of estrone in environmental and drinking water using molecularly imprinted solid phase extraction coupled with HPLC

Estrone has been identified as an important potential endocrine-disrupting compound, so that sensitive and reliable analytical methods are required for its determination and the assurance of human health. Using estrone as the template, acrylamide as the functional monomer, and methacryloxypropyltrimethoxysilane as the cross-linker, an organic-inorganic hybrid material has been synthesized by the molecular imprinting technique combined with a non-hydrolytic so-gel process. The synthesized polymer was characterized by FT-IR and static adsorption experiments, and the results showed that it had good recognition and selective ability for estrone. A novel method for separation and determination of trace estrone in water samples was developed using molecularly imprinted solid phase extraction coupled with HPLC. Under the selected experimental condition, the detection limit (S/N = 3) was 9.3 ng/L, and the RSD for five replicate extractions of 10 mug/L estrone was less than 5.0%. This method was employed for quantitative determination of estrone in river, lake, and tap water with recoveries ranging from 83.38 to 98.12%.