Molecularly imprinted polymer layer-coated silica nanoparticles toward dispersive solid-phase extraction of trace sulfonylurea herbicides from soil and crop samples

Selective quantification of diclofenac from groundwater and pharmaceutical samples by magnetic molecularly imprinted polymer-based sorbent coupled with the HPLC-PDA detection

Diclofenac (DCF) is a pharmaceutical contaminant of water bodies and therefore, improvement of analytical techniques for its removal and quantitation is one of the current interests of analysts. Herein, DCF selective magnetic molecularly imprinted polymer (MMIP) has been fabricated and characterized by Fourier transform-infrared spectroscopy, thermogravimetric analysis, vibrating scanning magnetometer, scanning electron microscopy, high-resolution transmission electron microscope, energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller analyzer. Furthermore, the protocol for the quantification of DCF using MMIP-HPLC-PDA combo has been optimized by investigating the effect of the amount of MMIP, type and volume of eluent, and variation of pH. The optimized protocol suggested a method detection limit of 0.042 ng mL^-1 and linearity of results in the range 0.1-100 ng mL^-1 (R² = 0.99). The fabricated material offered recovery of DCF up to 96.38-99.46% from groundwater and pharmaceutical samples with a relative standard deviation of <4%. In addition, the material was found selective and sensitive for DCF among its analogous drugs like mefenamic acid, ketoprofen, fenofibrate, aspirin, ibuprofen, and naproxen.

A Review on Recent Innovations of Pretreatment and Analysis Methods for Sulfonylurea Herbicides

Sulfonylurea herbicides (SUHs) are widely used in agriculture because of their low dosage, low cost, and high selectivity. However, due to improper use and lack of effective management, their residues pose a threat to the human health through environment and food pollution. Therefore, there is a need for simple, quick, economical, and effective methods to analyze SUHs in plant-derived foods, crops, and environmental samples. The present article presents a comprehensive review of the pretreatment and analytical technologies used for SUHs in various sample matrices, focusing on the developments since 2010. The main pretreatment methods include liquid-liquid extraction, solid-phase extraction, QuEChERS, and different microextraction methods, whereas analytical methods mainly include liquid chromatography coupled with different detectors, capillary electrophoresis, among others. In addition, the present study also compared the advantages and disadvantages of the methods and the future development is prospected.

Recent application of molecular imprinting technique in food safety

Due to the extensive use of chemical substances such as pesticides, antibiotics and food additives, food safety issues have gradually attracted people's attention. The extensive use of these chemicals seriously damages human health. In order to detect trace chemical residues in food, researchers have to find several simple, economical and effective tools for qualitative and quantitative analysis. As a kind of material that specifically and selectively recognize template molecules from real samples, molecular imprinting technique (MIT) has widely applied in food samples analysis. This article mainly reviews the application of molecularly imprinted polymer (MIP) in the detection of chemical residues from food in the past five years. Some recent and novel methods for fabrication of MIP are reviewed. Their application of sample pretreatment, sensors, etc. in food analysis is reviewed. The application of molecular imprinting in chromatographic stationary phase is referred. Additionally, the challenges faced by MIP are discussed.

Dual-template magnetic molecularly imprinted polymer-based sorbent for simultaneous and selective detection of phenolic endocrine disrupting compounds in foodstuffs

In this research, an efficient (94.9-99.4%) and fast (5 min) method has been developed and validated for simultaneous identification and quantification of phenolic endocrine disrupting compounds with an emphasis on bisphenol A (BPA) and 4-cumylphenol (4-CP) in food stuffs using a dual-template magnetic, molecularly-imprinted polymer (dt-MMIP). The dt-MMIP was synthesized by a sol-gel method using Fe₃O₄@SiO₂ (as the core) and BPA and 4-CP (as templates). The dt-MMIP was coupled with magnetic solid phase extraction to simultaneously detect BPA and 4-CP in food samples. BPA was measured from bottled water and fruit juice samples samples at 0.36 and 0.24 ng mL^-1, respectively, while 4-CP in those samples was 0.33 and 0.16 ng mL^-1, respectively. Their detection limits were estimated as 0.04 and 0.05 ng mL^-1, respectively. The developed dt-MMIP method was highly reproducible, while maintaining a good cyclability up to 20 cycles.

Preparation of molecularly imprinted polymer with class-specific recognition for determination of 29 sulfonylurea herbicides in agro-products

Molecularly imprinting polymers with high selectivity toward 29 sulfonylurea herbicides were synthesized by precipitation polymerization, using metsulfuron-methyl and chlorsulfuron as the template molecule, 4-vinylpyridine as the function monomer, divinylbenzene as the crosslinking agent, and acetonitrile as porogen. The imprinted polymers were characterized and measured by scanning electron microscopy (SEM) and equilibrium adsorption experiments. The molecularly imprinted polymers displayed specific recognition for the tested 29 sulfonylurea herbicides, and the maximum apparent binding capacity was found to be 18.81 mg/g. The synthesized polymer was used as a solid-phase extraction (SPE) column coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for determination of the tested analytes in agro-products. Within the range of 2-100 μg/L, the tested analytes have achieved a good linear association with correlation coefficient (R²) > 0.999. The calculated limits of detection (LODs, S/N=3) as along with limits of quantification (LOQs, S/N=10) were in the ranges of 0.005-0.07 μg/L and 0.018-0.23 μg/L, respectively. Under different spiking levels, the recovery rates were ranged from 74.8% - 110.5%, and the relative standard deviation (RSDs) were < 5.3%. Finally, the feasibility of the proposed methodology was successfully applied for detection of sulfonylurea herbicides in crops, vegetables, and oils samples.

Genetically Engineered Methanotroph as a Platform for Bioaugmentation of Chemical Pesticide Contaminated Soil

Bioaugmentation is a promising alternative in soil remediation. One challenge of bioaugmentation is that exogenous pollutant-degrading microbes added to soil cannot establish enough biomass to eliminate pollutants. Considering that methanotrophs have a growth advantage in the presence of methane, we hypothesize that genetically engineered methanotrophs could degrade contaminants efficiently in soil with methane. Here, methanotroph Methylomonas sp. LW13, herbicide bensulfuron-methyl (BSM), and two kinds of soil were chosen to confirm this hypothesis. The unmarked gene knock-in method was first developed for strain LW13. Then, BSM hydrolase encoding gene sulE was inserted into the chromosome of strain LW13, conferring it BSM-degrading ability. After inoculation, the cell amount of strain LW13-sulE in soil raised considerably (over 100 fold in 9 days) with methane provision; meanwhile, >90% of BSM in soil was degraded. This study provides a proof of the concept that genetically engineered methanotroph is a potential platform for soil remediation.

Theoretical research of molecular imprinted polymers formed from formaldehyde and methacrylic acid

In recent years, with the development of molecular imprinting technology, the imprinting sites, nature of imprinting, selection of functional monomers, cross-linking agents, solvents, and the optimization of the imprinting ratio are all the hot spots of researchers. In this work, the theoretical prediction of the self-assembly system of formaldehyde (HCHO) molecularly imprinted polymer was carried out by the B3LYP/6-31 G(d,p) method. The geometric configuration and active sites of the stable complex of HCHO and methacrylic acid (MAA) were analyzed. The selection of the imprinting ratios, cross-linking agents, and solvents was discussed. The topological properties of electron density of HCHO-MAA complex were considered by using the topological analysis method of chemical bond electron density based on valence bond theory. This study cannot only reveal the relationship between the imprinting mechanism of molecularly imprinted polymers and the molecular structure and properties of molecularly imprinted polymers but also provide valuable reference for the design and preparation of molecularly imprinted polymers.

Determination of sulfonylurea pesticide residues in edible seeds used as nutraceuticals by QuEChERS in combination with ultra-high-performance liquid chromatography-tandem mass spectrometry

This work proposes a novel Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) method in combination with ultra-high performance liquid chromatography-tandem mass spectrometry for the determination of sulfonylurea residues in edible seeds. The chromatographic separation of nine sulfonylureas was accomplished in less than 5.5 min, using a Luna Omega C₁₈ column (50 × 2.1 mm, 1.6 µm). Mobile phase was supplied at 0.55 mL min^-1 and consisted of 0.01% (v/v) aqueous acetic acid as eluent A and a mixture methanol/acetonitrile (80/20, v/v) as eluent B. Column temperature was established at 25 °C. A QuEChERS procedure was investigated as sample treatment for sulfonylureas extraction and sample clean-up. Different clean-up agents (i.e. PSA, Z-Sep⁺, EMR-Lipid and C¹⁸) were evaluated, selecting Z-Sep⁺ (25 mg) as the best option. The proposed method provided an extraction efficiency greater than 86.2%, while absolute matrix effect was lower than 50.1%. Matrix-matched calibration curves were required for analyte quantification. The analytical method was characterized according to SANTE/11813/2017 guideline, and including limits of detection and quantification, precision, and trueness. Linear dynamic ranges were established from 5 to 150 µg kg^-1 for all analytes. Linearity (R² ≥ 0.9974) and precision in terms of repeatability and intermediate precision (relative standard deviation ≤ 14.7%) are reported. The reporting limit was established at 5 µg kg^-1, which is above the limits of quantification of the proposed method (≤ 1.64 µg kg^-1) and below the maximum residue levels currently established by European legislation. In general, trueness is within the range of 70-120%. Despite greater recoveries were obtained at the reporting limit (i.e. 120-138%), relative standard deviations lower than 20% were obtained at this concentration level, so fulfilling the requirements of SANTE/11813/2017 guideline. This work represents the first analytical method intended for the analysis of sulfonylureas in sunflower, pumpkin and chia seeds, which are complex matrices due to their high content of fat as well as of growing interest due to their current commercialization as nutraceuticals.

Preparation of core-shell magnetic molecularly imprinted polymer nanoparticle for the rapid and selective enrichment of trace diuron from complicated matrices

A novel magnetic MIPs (DUMIPs) was prepared by surface molecular imprinting method using superparamagnetic core-shell nanoparticle (Fe₃O₄@SiO₂) as the sacrificial support matrix, herbicide diuron as template, α-methacrylic acid as the functional monomer, trimethylolpropane trimethacrylate as the crosslinker, azobisisobutyronitrile as the initiator, and acetonitrile as the porogen. Highly cross-linked porous surface and excellent magnetic property were characterized by Fourier-transform infrared spectroscopy, transmission electron microscopy, and vibrating sample magnetometer, respectively. The adsorption capacity of DUMIPs was 8.1 mg g^-1, 2.6-fold over its corresponding non-imprinted polymers (DUNIPs). The adsorption in DUMIPs was considered as multilayer adsorption and posed high affinity to diuron, due to the better fitting to Freundilich isotherm. Competitive recognition study demonstrated DUMIPs had highly selective binding diuron. DUMIPs, as an influential sorbent has been used for selective extraction of diuron from environmental samples (paddy field water, paddy soil and grain seedlings) and the elution was determined by high efficiency liquid chromatography (HPLC). In this analytical method, various factors affecting the extraction efficiency such as pH, sorbent dosage, utilization efficiency and volumes of eluent were simultaneously investigated. Under the optimal conditions, the linearity of the method obtained is in the range of 0.02-10.0 mg L^-1. The limit of detection is 0.012 mg L^-1. In four spiked levels (0.04, 0.2, 1.0, and 4.0 mg kg^-1), the recoveries of diuron in real samples are in the range of 83.56%-116.10% with relative standard deviations in the range of 1.21-6.81%. Importantly, compared to C₁₈-SPE column, the MMIPs exhibited convenient separation by external magnetic field, strong clean-up capacity, and selective enrichment for diuron. Thus, the DUMIPs-based method is great potential for efficient sample preparation in the determination of trace amounts of diuron residues in complex matrices.

CdS quantum dots-based immunoassay combined with particle imprinted polymer technology and laser ablation ICP-MS as a versatile tool for protein detection

For the first time, the combination of molecularly imprinted polymer (MIP) technology with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is presented with focus on an optimization of the LA-ICP-MS parameters such as laser beam diameter, laser beam fluence, and scan speed using CdS quantum dots (QDs) as a template and dopamine as a functional monomer. A non-covalent imprinting approach was employed in this study due to the simplicity of preparation. Simple oxidative polymerization of the dopamine that creates the self-assembly monolayer seems to be an ideal choice. The QDs prepared by UV light irradiation synthesis were stabilized by using mercaptosuccinic acid. Formation of a complex of QD-antibody and QD-antibody-antigen was verified by using capillary electrophoresis with laser-induced fluorescence detection. QDs and antibody were connected together via an affinity peptide linker. LA-ICP-MS was employed as a proof-of-concept for detection method of two types of immunoassay: 1) antigen extracted from the sample by MIP and subsequently overlaid/immunoreacted by QD-labelled antibodies, 2) complex of antigen, antibody, and QD formed in the sample and subsequently extracted by MIP. The first approach provided higher sensitivity (MIP/NIP), however, the second demonstrated higher selectivity. A mixture of proteins with size in range 10–250 kDa was used as a model sample to demonstrate the capability of both approaches for detection of IgG in a complex sample.

A Novel Metal-Organic Framework Composite, MIL-101(Cr)@MIP, as an Efficient Sorbent in Solid-Phase Extraction Coupling with HPLC for Tribenuron-Methyl Determination

A highly efficient and selective method based on core–shell molecularly imprinted polymers (MIL@MIP) and high performance liquid chromatography (HPLC) was developed and firstly used for the trace analysis of tribenuron-methyl (TBM) in complicated matrices. The MIL@MIP was prepared by surface molecular-imprinting technique, specially using MIL-101 as core, TBM as template molecule, methacrylic acid (MAA) as functional monomer, ethylene glycol dimethacrylate (EGDMA) as cross-linker, and azobisisobutyronitrile (AIBN) as initiator. The resulting MIL@MIP showed high affinity, recognition specificity, fast mass transfer rate, and efficient adsorption performance towards TBM with the adsorption capacity reaching up to 3.217 mg/g. It also showed high cross-selectivity for TBM among its six kinds of chemical structure analogues. Furthermore, using the MIL@MIP as solid-phase extraction (SPE) materials, the recoveries of TBM determined by HPLC were 84.6-92.3%, 93.3-106.7%, and 88.9-93.3% in the spiked river water, soil, and soybean samples, respectively, with the limit of detection of 0.3 ng/L, 1.5 ng/kg, and 1.5 ng/kg, accordingly. It was proved that the developed HPLC-MISPE method was fast, accurate, and sensitive for detecting the trace TBM in river water, soil, and soybean samples.

Voltammetric immunoassay of human IgG based on the release of cadmium(II) from CdS nanocrystals deposited on mesoporous silica nanospheres

The authors describe a nanocomposite that was obtained by in-situ deposition of CdS nanocrystals on mesoporous silica nanospheres (MSNs), and its use in an electrochemical immunoassay of human immunoglobulin G (HIgG). The MCN/CdS nanocomposite was covalently modified with the antibodies against HIgG and then employed in a voltammetric immunoassay at antibody-functionalized magnetic beads. Through sandwich immunoreaction, the MCN/CdS nanoprobes are quantitatively captured onto the magnetic beads where numerous Cd(II) ions are released in an acidic solution. The Cd(II) can be detected by anodic stripping voltammetry at a typical working potential of -0.78 V (vs. Ag/AgCl). In combination with the high loading of CdS on MSNs, the use of the stripping voltammetric analysis renders the method high sensitivity. A wide linear range varying from 0.01 to 100 ng mL^-1 is obtained for HIgG detection with a lower detection limit at 2.9 pg mL^-1. In addition, the preparation of the nanoprobe is inexpensive. The magnetic bead-based assay does not require complex manipulations. Therefore, this method is deemed to possess a wide scope in that it may be applied to other immunoassays. Graphical abstract Graphical Abstract contains poor quality and small text inside the artwork. Please do not re-use the file that we have rejected or attempt to increase its resolution and re-save. It is originally poor, therefore, increasing the resolution will not solve the quality problem. We suggest that you provide us the original format. We prefer replacement figures containing vector/editable objects rather than embedded images. Preferred file formats are eps, ai, tiff and pdf.A TIFF file at 900 dpi resolution of the Graphical Abstract has been attached via this online system. Schematic presentation of the preparation of the mesoporous silica nanosphere (MSN)/CdS nanocomposite for the electrochemical immunoassay of human IgG at magnetic beads. The high decoration of CdS on MSN and the stripping voltammetric analysis of Cd(II) ions render the method high sensitivity.

Advancements of molecularly imprinted polymers in the food safety field

Molecularly imprinted technology (MIT) has been widely employed to produce stable, robust and cheap molecularly imprinted polymer (MIP) materials that possess selective binding sites for recognition of target analytes in food, such as pesticides, veterinary drugs, mycotoxins, illegal drugs and so on. Because of high selectivity and specificity, MIPs have drawn great attention in the food safety field. In this review, the recent developments of MIPs in various applications for food safety, including sample preparation, chromatographic separation, sensing, immunoassay etc., have been summarized. We particularly discuss the advancements and limitations in these applications, as well as attempts carried out for their improvement.

Development and application of a novel fluorescent nanosensor based on FeSe quantum dots embedded silica molecularly imprinted polymer for the rapid optosensing of cyfluthrin

A novel molecularly imprinted silica layer appended to FeSe quantum dots (MIP-FeSe-QDs) was fabricated and utilized as a recognition element to develop a selective and sensitive fluorescent nanosensor for cyfluthrin (CYF) determination. The MIP-FeSe-QDs were characterized by fluorescence spectrometry, scanning electron microscopy, transmission electron microscopy, and Fourier transform infrared spectroscopy. Excellent selectivity and high sensitivity of MIP-FeSe-QDs to CYF molecules were observed based on the fluorescence quenching of FeSe-QDs. Under optimal conditions, a good linear relationship was found between fluorescence quenching effect and increased CYF concentration within 0.010-0.20mg/L, with a correlation coefficient of 0.9911. The practicality of the developed sensor method for CYF detection in fish and sediment samples was further validated. Good recoveries ranging from 88.0% to 113.9% with<6.8% relative standard deviations were obtained. The detection limits of CYF in sediment and fish samples were 1.3 and 1.0µg/kg, respectively. This study established a novel, rapid fluorescent nanosensor detection method based on MIP-QDs for successfully analyzing CYF in fish and sediment samples.

Superparamagnetic graphene oxide-based dispersive-solid phase extraction for preconcentration and determination of tamsulosin hydrochloride in human plasma by high performance liquid chromatography-ultraviolet detection

In the present study, superparamagnetic graphene oxide-Fe₃O₄ nanocomposites were successfully prepared by a modified impregnation method (MGO_mi) and their application as a sorbent in the magnetic-dispersive solid phase extraction (M-dSPE) mode to the preconcentration and determination of tamsulosin hydrochloride (TMS) in human plasma was investigated by coupling with high performance liquid chromatography-ultraviolet detection (HPLC-UV). The structure, morphology and magnetic properties of the prepared nanocomposites were characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and vibrating sample magnetometry (VSM). Some factors affecting the extraction efficiency, including the pH value, amount of sorbent, extraction time, elution solvent and its volume, and desorption time were studied and optimized. Magnetic nanocomposites plasma extraction of TMS following HPLC analyses showed a linear calibration curve in the range of 0.5-50.0ngmL^-1 with an acceptable correlation coefficient (R²=0.9988). The method was sensitive, with a low limit of detection (0.17ngmL^-1) and quantification (0.48ngmL^-1). Inter- and intra-day precision expressed as relative standard deviation (n=3) and the preconcentration factor, were found to be 5.6-7.2%, 2.9-4.2% and 10, respectively. Good recoveries (98.1-101.4%) with low relative standard deviations (4.2-5.0%) indicated that the matrices under consideration do not significantly affect the extraction process. Due to its high precision and accuracy, the developed method may be a HPLC-UV alternative with M-dSPE for bioequivalence analysis of TMS in human plasma.

Nanomaterials for sample pretreatment prior to capillary electrophoretic analysis

Nanomaterials are, in analytical science, used for a broad range of purposes, covering the area of sample pretreatment as well as separation, detection and identification of target molecules.

Silica nanoparticle based techniques for extraction, detection, and degradation of pesticides

Silica nanoparticles (SiNPs) find applications in the fields of drug delivery, catalysis, immobilization and sensing. Their synthesis can be mediated in a facile manner and they display broad range compatibility and stability. Their existence in the form of spheres, wires and sheets renders them suitable for varied purposes. This review summarizes the use of silica nanostructures in developing techniques for extraction, detection and degradation of pesticides. Silica nanostructures on account of their sorbent properties, porous nature and increased surface area allow effective extraction of pesticides. They can be modified (with ionic liquids, silanes or amines), coated with molecularly imprinted polymers or magnetized to improve the extraction of pesticides. Moreover, they can be altered to increase their sensitivity and stability. In addition to the analysis of pesticides by sophisticated techniques such as High Performance Liquid Chromatography or Gas chromatography, silica nanoparticles related simple detection methods are also proving to be effective. Electrochemical and optical detection based on enzymes (acetylcholinesterase and organophosphate hydrolase) or antibodies have been developed. Pesticide sensors dependent on fluorescence, chemiluminescence or Surface Enhanced Raman Spectroscopic responses are also SiNP based. Moreover, degradative enzymes (organophosphate hydrolases, carboxyesterases and laccases) and bacterial cells that produce recombinant enzymes have been immobilized on SiNPs for mediating pesticide degradation. After immobilization, these systems show increased stability and improved degradation. SiNP are significant in developing systems for effective extraction, detection and degradation of pesticides. SiNPs on account of their chemically inert nature and amenability to surface modifications makes them popular tools for fabricating devices for 'on-site' applications.

Development of dummy molecularly imprinted based on functionalized silica nanoparticles for determination of acrylamide in processed food by matrix solid phase dispersion

A novel technique was applied for the synthesis of dummy molecularly imprinted silica nanoparticles (DMISNPs). DMISNPs were characterized by Fourier transmission infrared spectrometry, scanning electron microscopy and transmission electron microscope. The material was used as dispersant for the analysis of biscuit and bread samples using matrix solid phase dispersion (MSPD). Of advantages of such approach may be counted as the simplicity of synthesis procedure, low consumption of organic solvent, mild working temperature during the synthesis, high binding capacity and affinity. The effect of various parameters such as sample-to-dispersant ratio and eluents volume on extraction recovery was investigated and optimized by central composite design under response surface methodology. It was proven that the proposed dispersant leads to high affinity toward acrylamide even in complicated matrices. Quantification of the acrylamide was carried out by high performance liquid chromatography with UV detection (HPLC-UV).

Selective dispersive solid phase extraction-chromatography tandem mass spectrometry based on aptamer-functionalized UiO-66-NH2 for determination of polychlorinated biphenyls

In this paper, a novel dispersive solid phase extraction (dSPE) adsorbent based on aptamer-functionalized magnetic metal-organic framework material was developed for selective enrichment of the trace polychlorinated biphenyls (PCBs) from soil sample. Firstly, we developed a simple, versatile synthetic strategy to prepare highly reproducible magnetic amino-functionalized UiO-66 (Fe3O4@PDA@UiO-66-NH2) by using polydopamine (PDA) as covalent linker. Then amino-functionalized aptamers which can recognize 2,3',5,5'-tetrachlorobiphenyl (PCB72), 2',3',4',5,5'-pentachlorobiphenyl (PCB106) were covalent immobilized on UiO-66-NH2 through coupling reagent of glutaraldehyde. Aptamer-functionalized adsorbent (Fe3O4@PDA@UiO-66-Apt) can specifically capture PCBs from complex matrix with high adsorption capacity based on the specific affinity of aptamer towards target. Moreover, the adsorbent can be easily isolated from the solution through magnetic separation after extraction. Afterwards, the detection was carried out with gas chromatography tandem mass spectrometry (GC-MS). The selective dSPE pretreatment coupled with GC-MS possessed high selectivity, good binding capacity, stability, repeatability and reproducibility for the extraction of PCBs. Furthermore, the adsorbent possessed good mechanical stability which can be applied in replicate at least for 60 extraction cycles with recovery over 80%. It provided a linear range of 0.02-400ngmL(-1) with a good correlation coefficient (R(2)=0.9994-0.9996), and the limit of detection was found to be 0.010-0.015ngmL(-1). The method was successfully utilized for the determination of PCBs in soil samples.

Molecular imprinting: perspectives and applications

This critical review presents a survey of recent developments in technologies and strategies for the preparation of MIPs, followed by the application of MIPs in sample pretreatment, chromatographic separation and chemical sensing.

A new magnetic tailor made polymer for separation and trace determination of cadmium ions by flame atomic absorption spectrophotometry

Magnetic ion imprinted polymers have been prepared and applied for the selective extraction and trace monitoring of cadmium ions in food samples.

Imprinted silica nanoparticles coated with N-propylsilylmorpholine-4-carboxamide for the determination of m-cresol in synthetic and real samples

m-Cresol-imprinted silica nanoparticles coated with N-propylsilylmorpholine-4-carboxamide have been developed that contain specific pockets for the selective uptake of m-cresol. Silica nanoparticles were synthesized by a sol-gel process followed by functionalization of their surface with N-propylsilylmorpholine-4-carboxamide. The formation of m-cresol-imprinted silica nanoparticles was confirmed by UV-Vis spectrophotometry, infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy and transmission electron microscopy. Electron microscopic studies revealed the formation of monodispersed imprinted silica nanoparticles with spherical shape and an average size of 83 nm. The developed nanoparticles were filled in a syringe and used for the extraction of m-cresol from aqueous samples followed by quantification using high-performance liquid chromatography with diode array detection. Various adsorption experiments showed that developed m-cresol-imprinted silica nanoparticles exhibited a high adsorption capacity and selectivity and offered a fast kinetics for rebinding m-cresol. The chromatographic quantification was achieved using mobile phase consisting of acetonitrile/water (70:30 v/v) at an isocratic flow rate of 1.0 mL/min using a reversed-phase C18 column and detection at λmax = 275 nm. The limits of detection and quantification were 1.86 and 22.32 ng/mL, respectively, for the developed method. The percent recoveries ranged from 96.66-103.33% in the spiked samples. This combination of this nanotechnique with molecular imprinting was proved as a reliable, sensitive and selective method for determining the target from synthetic and real samples.

Core-shell magnetic molecularly imprinted polymers as sorbent for sulfonylurea herbicide residues

Sulfonylurea herbicides are widely used at lower dosage for controlling broad-leaf weeds and some grasses in cereals and economic crops. It is important to develop a highly efficient and selective pretreatment method for analyzing sulfonylurea herbicide residues in environments and samples from agricultural products based on magnetic molecularly imprinted polymers (MIPs). The MIPs were prepared by a surface molecular imprinting technique especially using the vinyl-modified Fe3O4@SiO2 nanoparticle as the supporting matrix, bensulfuron-methyl (BSM) as the template molecule, methacrylic acid (MAA) as a functional monomer, trimethylolpropane trimethacrylate (TRIM) as a cross-linker, and azodiisobutyronitrile (AIBN) as an initiator. The MIPs show high affinity, recognition specificity, fast mass transfer rate, and efficient adsorption performance toward BSM with the adsorption capacity reaching up to 37.32 mg g(-1). Furthermore, the MIPs also showed cross-selectivity for herbicides triasulfuron (TS), prosulfuron (PS), and pyrazosulfuron-ethyl (PSE). The MIP solid phase extraction (SPE) column was easier to operate, regenerate, and retrieve compared to those of C18 SPE column. The developed method showed highly selective separation and enrichment of sulfonylurea herbicide residues, which enable its application in the pretreatment of multisulfonylurea herbicide residues.

Simultaneous determination of acidic pesticides in vegetables and fruits by liquid chromatography--tandem mass spectrometry

A sensitive and efficient method has been developed for the simultaneous determination of 73 multi-class acidic pesticides, such as phenoxy acid and sulfonylurea herbicides, in vegetables and fruits. The sample preparation procedure was carefully optimized for the efficient removal of co-extracted matrix components. The method involves extraction of acidic pesticides with acetonitrile containing hydrochloric acid, removal of water from crude extract by salting out, and sequential cleanup by octadecylsilyl silica gel and silica gel columns. For samples containing high amounts of pigments, such as spinach, additional cleanup using a graphitized carbon column was performed prior to liquid chromatography-mass spectrometry (LC-MS/MS) analysis. Recovery tests were performed for five times for each sample of cabbage, spinach, potato, eggplant, orange, and apple fortified at 0.01 mg kg-1. Out of the 73 tested pesticides, 70 for cabbage, 67 for spinach, 69 for potato, 67 for eggplant, 64 for orange, and 70 for apple were within the range of 70-120%, with relative standard deviations below 25%. Nitenpyram and pyrasulfotole showed low recoveries for all the samples tested, probably due to low recoveries from silica gel column. The developed method effectively removed co-extracted matrix components and was highly selective, with no interfering peaks found in the chromatograms of blank samples. The overall results indicate that the developed method is suitable for the quantitative analysis of acidic pesticide residues in vegetables and fruits.

Monodisperse magnetic ion imprinted polymeric microparticles prepared by RAFT polymerization based on γ-Fe2O3@meso-SiO2nanospheres for selective solid-phase extraction of Cu(ii) in water samples

Utilising a general protocol for making surface-imprinted core–shell microparticlesviaa RAFT-mediated approach, we developed a Cu(ii) imprinted polymer with a novel magnetic nanosphere, γ-Fe₂O₃@meso-SiO₂, as support.

Molecular imprinting science and technology: a survey of the literature for the years 2004-2011

Herein, we present a survey of the literature covering the development of molecular imprinting science and technology over the years 2004-2011. In total, 3779 references to the original papers, reviews, edited volumes and monographs from this period are included, along with recently identified uncited materials from prior to 2004, which were omitted in the first instalment of this series covering the years 1930-2003. In the presentation of the assembled references, a section presenting reviews and monographs covering the area is followed by sections describing fundamental aspects of molecular imprinting including the development of novel polymer formats. Thereafter, literature describing efforts to apply these polymeric materials to a range of application areas is presented. Current trends and areas of rapid development are discussed.

Interfacial molecular imprinting of Stöber particle surfaces: a simple approach to targeted saccharide adsorption

The use of surfactant headgroups for interfacial imprinting is established as a simple and tunable approach to create molecularly imprinted silica nanoparticles based on a modification of the Stöber method. Adsorption of D-glucose and D-xylose (initial concentrations ranging from 0.139 to 1.67 mol/l) is measured on silica nanoparticles created by the addition of a glucose-based surfactant (n-octyl-β-D-glucopyranoside (C8G1)) or surfactant mixtures (C8G1 and cetyltrimethylammonium bromide (CTAB)) to Stöber particles shortly after their precipitation. Silica particles synthesized in the presence of C8G1 as an imprinting surfactant have a significantly higher affinity for glucose over xylose (as much as 3.25 times greater at 0.25 M saccharide), and an enhanced affinity for glucose relative to non-imprinted silica particles (as much as 4 times greater at 0.25 M), which adsorb glucose and xylose similarly. Glucose imprinting is significantly enhanced using a surfactant mixture of 1:1 C8G1/CTAB. The interfacial activity of the nonionic imprinting surfactant at the silica surface is suggested to be improved by the presence of interfacial cationic CTAB, which is driven to the silica surface through electrostatic interactions. The concept of imprinting through the interaction of surfactant headgroups with the soft surface of silica particles is supported by the importance of the time of addition of the surfactants. The greatest enhancement in glucose adsorption is observed when the surfactants are added 1 min after precursor addition (at the onset of aggregated particle formation, as indicated by solution turbidity) and the silica affinity for glucose decreases with the time of surfactant addition. The versatility of the surfactant imprinting of Stöber particles is demonstrated by the enhanced adsorption of xylose relative to glucose on particles imprinted using a 1:1 mixture of n-octyl-β-D-xylopyranoside and CTAB, suggesting that the process can be customized to selectively adsorb target molecules of interest.