Selective mixed-bed solid phase extraction of atrazine herbicide from environmental water samples using molecularly imprinted polymer

Molecularly Imprinted Polymer-Based Sensors for Priority Pollutants

Globally, there is growing concern about the health risks of water and air pollution. The U.S. Environmental Protection Agency (EPA) has developed a list of priority pollutants containing 129 different chemical compounds. All of these chemicals are of significant interest due to their serious health and safety issues. Permanent exposure to some concentrations of these chemicals can cause severe and irrecoverable health effects, which can be easily prevented by their early identification. Molecularly imprinted polymers (MIPs) offer great potential for selective adsorption of chemicals from water and air samples. These selective artificial bio(mimetic) receptors are promising candidates for modification of sensors, especially disposable sensors, due to their low-cost, long-term stability, ease of engineering, simplicity of production and their applicability for a wide range of targets. Herein, innovative strategies used to develop MIP-based sensors for EPA priority pollutants will be reviewed.

Rational Design of Molecularly Imprinted Polymers Using Quaternary Ammonium Cations for Glyphosate Detection

Molecularly imprinted polymers have emerged as cost-effective and rugged artificial selective sorbents for combination with different sensors. In this study, quaternary ammonium cations, as functional monomers, were systematically evaluated to design imprinted polymers for glyphosate as an important model compound for electrically charged and highly water-soluble chemical compounds. To this aim, a small pool of monomers were used including (3-acrylamidopropyl)trimethylammonium chloride, [2-(acryloyloxy)ethyl]trimethylammonium chloride, and diallyldimethylammonium chloride. The simultaneous interactions between three positively charged monomers and glyphosate were preliminary evaluated using statistical design of the experiment method. Afterwards, different polymers were synthesized at the gold surface of the quartz crystal microbalance sensor using optimized and not optimized glyphosate-monomers ratios. All synthesized polymers were characterized using atomic force microscopy, contact angle, Fourier-transform infrared, and X-ray photoelectron spectroscopy. Evaluated functional monomers showed promise as highly efficient functional monomers, when they are used together and at the optimized ratio, as predicted by the statistical method. Obtained results from the modified sensors were used to develop a simple model describing the binding characteristics at the surface of the different synthesized polymers. This model helps to develop new synthesis strategies for rational design of the highly selective imprinted polymers and to use as a sensing platform for water soluble and polar targets.

Fluorometric determination of sulfadiazine by using molecularly imprinted poly(methyl methacrylate) nanobeads doped with manganese(II)-doped ZnS quantum dots

The surface of poly(methyl methacrylate) nanospheres (PMMA-NSs) was molecularly imprinted with sulfadiazine by a surface imprinting method. Simultaneously, Mn(II)-doped ZnS quantum dots were incorporated into the imprinted PMMA-NSs. The morphology of the fluorescent nanoprobe was characterized by transmission electron microscopy which revealed good spheroidal core-shell structure and a homogeneous distribution of the QDs. Following binding of sulfadiazine, fluorescence (best measured at excitation/emission maxima of 335/592 nm) is increasingly quenched. The detection range is 5-40 μmol·L^-1 of sulfadiazine, and the detection limit is 0.24 μmol·L^-1. The fluorescence quenching mechanism is discussed, and a photo-induced electron transfer process is shown to account for quenching. The fluorescent probe was applied to the determination of sulfadiazine in spiked tap water with recoveries and RSDs of 96.6-100.2% and 2.7-3.9%, respectively. The detection of sulfadiazine in spiked lake water exhibited the recoveries and RSDs with 99.3-104.8% and 1.8-4.2%, respectively. Graphical abstract Schematic presentation of synthesis of PMMA-Ns, Mn-doped ZnS QDs, MQPs, and the elution diagram of SD from MQPs, and the relative reagents including: sodium dodecyl benzene sulfonate(SDBS), (3-aminopropyl)triethoxysilane(APTES), 3-mercaptopropionic acid (MPA), tetraethylorthosilicate(TEOS)and sulfadiazine(SD), and nanoparticles including: polymer(methyl methacrylate) nanospheres(PMMANs), MIPs@QDs@PMMANs(MQPs) and carbon quantum dots(CQDs).

Synthesis of molecularly imprinted nanoparticles for selective exposure assessment of permethrin: optimization by response surface methodology

BACKGROUND

Extensive use of high-efficiency pyrethroid pesticides as pest-control agents lead to remarkable adsorption and release of these materials in soil and aquatic environment which could have serious adverse effects on water and food chain quality as well as human health. In this study, a molecularly imprinted polymer was synthesized and used as a selective sorbent in the sample preparation procedure in order to facilitate sensitive and quantitative exposure assessment of insecticide permethrin.

METHODS

Molecular imprinted nanoparticles were prepared by precipitation polymerization technique using 1:4:20 mmol ratio of the template, functional monomer, and cross-linker, respectively, as well as 80 mL of chloroform as progen solvent. The obtained nanoparticles were characterized by field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectrometry (FT-IR). The optimization of critical variables in the MISPE process was done using the central composite design (CCD) of the response surface methodology.

RESULTS

Quadratic regressional models were developed to correlate the response and independent variables and the analysis of variance (ANOVA) verified the excellent fitting of proposed models for experimental data. Optimum conditions for the highest MISPE yield were selected as follow: sorbent mass of 7.71 mg, sample pH 5.58 and 5.68 for cis and trans-permethrin, respectively, sample flow rate of 0.6 mL/min, as well as 5 and 3.94 mL of methanol/acetic acid at the flow rate of 2 mL/min as elution solvents for cis and trans-permethrin, respectively. Under optimized conditions, the linear range was obtained 20-120 μg/L (R2 = 0.99) and the detection limits were 5.51 and 5.72 μg/L for cis and trans-permethrin, respectively. Analysis of real samples demonstrated the high extraction efficiency of designed protocol ranging from 93.01 to 97.14 with the relative standard deviation (RSD) less than 4.51%.

CONCLUSIONS

The satisfactory results confirmed the reliability and efficiency of the proposed method for trace analysis of permethrin isomers in biological and environmental samples.

Molecularly Imprinted Polymer Materials as Selective Recognition Sorbents for Explosives: A Review

Explosives are of significant interest to homeland security departments and forensic investigations. Fast, sensitive and selective detection of these chemicals is of great concern for security purposes as well as for triage and decontamination in contaminated areas. To this end, selective sorbents with fast binding kinetics and high binding capacity, either in combination with a sensor transducer or a sampling/sample-preparation method, are required. Molecularly imprinted polymers (MIPs) show promise as cost-effective and rugged artificial selective sorbents, which have a wide variety of applications. This manuscript reviews the innovative strategies developed in 57 manuscripts (published from 2006 to 2019) to use MIP materials for explosives. To the best of our knowledge, there are currently no commercially available MIP-modified sensors or sample preparation methods for explosives in the market. We believe that this review provides information to give insight into the future prospects and potential commercialization of such materials. We warn the readers of the hazards of working with explosives.

Simultaneous determination of paraquat and atrazine in water samples with a white light reflectance spectroscopy biosensor

An optical immunosensor based on White Light Reflectance Spectroscopy for the simultaneous determination of the herbicides atrazine and paraquat in drinking water samples is demonstrated. The biosensor allows for the label-free real-time monitoring of biomolecular interactions taking place onto a SiO₂/Si chip by transforming the shift in the reflected interference spectrum due to reaction to effective biomolecular layer thickness. Dual-analyte determination is accomplished by functionalizing spatially distinct areas of the chip with protein conjugates of the two herbicides and scanning the surface with an optical reflection probe. A competitive immunoassay format was adopted, followed by reaction with secondary antibodies for signal enhancement. The sensor was highly sensitive with detection limits of 40 and 50 pg/mL for paraquat and atrazine, respectively, and the assay duration was 12 min. Recovery values ranging from 90.0 to 110% were determined for the two pesticides in spiked bottled and tap water samples, demonstrating the sensor accuracy. In addition, the sensor could be regenerated and re-used at least 20 times without significant effect on the assay characteristics. Its excellent analytical performance and short analysis time combined with the small sensor size should be helpful for fast on-site determinations of these analytes.

Determination of Ten Macrolide Drugs in Environmental Water Using Molecularly Imprinted Solid-Phase Extraction Coupled with Liquid Chromatography-Tandem Mass Spectrometry

With the extensive application of antibiotics in livestock, their contamination of the aquatic environment has received more attention. Molecularly imprinted polymer (MIP), as an eco-friendly and durable solid-phase extraction material, has shown great potential for the separation and enrichment of antibiotics in water. This study aims at developing a practical and economical method based on molecularly imprinted solid phase extraction (MISPE) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for simultaneously detecting ten macrolide drugs in different sources of water samples. The MIP was synthesized by bulk polymerization using tylosin as the template and methacrylic acid as the functional monomer. The MIP exhibited a favorable load-bearing capacity for water (>90 mL), which is more than triple that of non-molecularly imprinted polymers (NIP). The mean recoveries of macrolides at four spiked concentration levels (limit of quantification, 40, 100, and 400 ng/L) were 62.6–100.9%, with intra-day and inter-day relative standard deviations below 12.6%. The limit of detection and limit of quantification were 1.0–15.0 ng/L and 3.0–40.0 ng/L, respectively. Finally, the proposed method was successfully applied to the analysis of real water samples.

MOF-5(Zn)-Fe2O4 nanocomposite based magnetic solid-phase microextraction followed by HPLC-UV for efficient enrichment of colchicine in root of colchicium extracts and plasma samples

In present work, facile method is developed for determination of colchicine in human plasma sample, autumn and spring root of colchicium extracts by ultrasound assisted dispersive magnetic solid phase microextraction followed by HPLC-UV method (UAD-MSPME-HPLC-UV). Magnetic (Fe₂O₄-nanoparticles) metal organic framework-5, (MOF-5(Zn)-Fe₂O₄NPs) was synthesized by dispersing MOF-5 and Fe(NO₃)₃.9H₂O in ethylene glycol (as capping agent) and NaOH (pH adjustment agent) by hydrothermal method. The prepared sorbent was characterized via XRD and SEM analysis and applied as magnetic solid phase in UAD-MSPME-HPLC-UV method. In this method, colchicine molecules were sorbed on MOF-5(Zn)-Fe₂O₄NPs sorbent by various mechanisms like ion exchange, hydrogen bonding and electrostatic, ᴨ-ᴨ, hard-hard and dipole-ion interaction followed by exposing sonication waves as incremental mass transfer agent and then the sorbent was separated from the sample matrix by an external magnetic fields. Subsequently, accumulated colchicine were eluted by small volume of desorption organic solvent. Influence of operational variables such as MOF-5(Zn)-Fe₂O₄NPs mass, volume of extracting solvent and sonication time on response property (recovery) were studied and optimized by central composite design (CCD) combined with desirability function (DF) approach. Under optimum condition, the method has wide linear calibration rang (0.5-1700ngmL^-1) with reasonable detection limit (0.13ngmL^-1) and R²=0.9971. Finally, the UAD-MSPME-HPLC-UV method was successfully applied for determination of colchicine autumn and spring root of colchicium extracts and plasma samples.

Selective solid phase extraction of chloroacetamide herbicides from environmental water samples by amphiphilic magnetic molecularly imprinted polymers

In this study, a novel amphiphilic magnetic molecularly imprinted polymers (MMIPs) have been prepared by using Fe₃O₄ microspheres as the magnetic core, 4-vinyl pyridine (4-VP) and alkenyl glycosides glucose (AGG) as functional co-monomers. Fe₃O₄ microspheres were directly encapsulated by the polymer without any surface modification in the distillation-precipitation polymerization. The morphology and composition of MMIPs were characterized by X-ray diffraction (XRD), vibrating sample magnetometry (VSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Binding property and magnetic separation ability were systematically investigated through the equilibrium binding experiments. The feasibility of magnetic molecular imprinted solid phase extraction (MMISPE) was investigated for the selective enrichment of chloroacetamide herbicides from environmental water samples. The developed MMISPE-HPLC method exhibited good linearity (0.1-200μgL^-1), low limit of detection (0.03-0.06μgL^-1), and good precision (RSD<7%) under the optimized conditions. The introduced MMISPE-HPLC method was successfully used to analyze chloroacetamide herbicides in environmental water samples. Spiked chloroacetamide herbicides recoveries in three water samples ranged from 82.1% to 102.9%. These results indicated that amphiphilic MMIPs were the promising sorbents for the selective enrichment of chloroacetamide herbicides at trace levels from real environmental water samples.

Removal of triazine-based herbicides on specific polymeric sorbent: fixed bed column studies

The porous material containing carboxyl groups was investigated in fixed bed system for the triazine-based herbicides removal from aqueous solution. In order to obtain adsorbent capable of generating specific interactions with triazines, the poly(divinylbenzene) was synthesized in radical suspension polymerization and then was modified with maleic anhydride in Diels-Alder reaction with subsequent base hydrolysis. The introduction of carboxyl groups into polymer structure resulted in obtaining specific interactions, such as hydrogen bonds between modified poly(divinylbenzene) and triazines, therefore the selectivity and the high adsorption capacity towards terbuthylazine, propazine, atrazine and simazine was observed. The total and usable adsorptive capacities, the breakthrough and exhaustion times, the coefficients of sphericity of isoplanes, the heights of adsorption fronts and the mass exchange moving rates were calculated based on the analysis of the breakthrough curves. Results show that the best sorption parameters in dynamic conditions were achieved for terbuthylazine and propazine. For them the highest values of adsorptive capacities, the smallest heights of mass transfer fronts and their slow movement along the bed height were obtained. The use of ethanol for herbicides elution provided a high recovery degree of adsorbed substances. Reusability of investigated polymer bed was studied in three adsorption/desorption cycles.

Removal of triazine-based herbicides on specific polymeric sorbent: batch studies

The triazine-based herbicides removal from aqueous solution on specific polymeric adsorbent was studied. Poly(divinylbenzene) modified with maleic anhydride in Diels-Alder reaction was selected for the sorption experiments because molecular structures of triazine derived herbicides exhibit complementarity to the arrangement of functional groups in the polymer. The presence of carboxyl groups in adsorbent structure resulted in specific directional interactions, such as hydrogen bonds, which can intensify adsorption ability towards triazines. In the case of both atrazine and terbuthylazine the effect is more intensive, whereas in sorption of simazine and propazine the non-specific interactions have higher importance than hydrogen bonds. Specific interactions in investigated systems are between the hydrogen atom of the amino group of triazine and the carbonyl oxygen atom of the carboxyl group of the modified poly(divinylbenzene) (O…H–N). Only in the case of terbuthylazine the creation of hydrogen bonds between hydroxyl hydrogen atom of carboxylic group and nitrogen atom containing free electron pair from triazine (O–H…N) was observed. The sorption of simazine, atrazine and propazine does not depend on pH in the acidic region, whereas in the case of terbuthylazine an increase in sorption efficiency is observed while pH decreases.

Evaluation of flow injection analysis method with spectrophotometric detection for the determination of atrazine in soil extracts

A method for determining atrazine in soil extracts was evaluated by flow injection analysis with spectrophotometric detection. The method is based on the reaction of atrazine with pyridine in an acid medium followed by the reaction with NaOH and sulfanilic acid. Several analytical conditions were previously studied and optimized. Under the best conditions of analysis, the limits of detection and quantification were 0.15 and 0.45 mg L(-1), respectively, for a linear response between 0.50 and 2.50 mg L(-1), and a sampling throughput of 21 determinations per hour. Using the standard addition method, the maximum relative standard deviation of 17% and recovery values between 80 and 100% were observed for three extracts from soil samples with different composition. The proposed method is simple, low-cost and easy to use, and can be employed for studies involving atrazine in soil samples or for screening of atrazine in soils.

Selective extraction and concentration of mebendazole in seawater samples using molecularly imprinted polymer as sorbent

A high selective pre-treatment method for the extraction and analysis of mebendazole in environmental water samples was developed based on molecularly imprinted solid-phase extraction (MISPE). The mebendazole imprinted polymers were synthesized in acetonitrile using methacrylic acid and ethylene glycol dimethacrylate as functional monomer and cross-linker respectively. The imprinted materials showed high adsorption ability for mebendazole and were applied as special solid-phase extraction sorbents for selective separation of mebendazole. An off-line MISPE procedure was developed for the purification and enrichment of mebendazole from natural seawater samples prior to high-performance liquid chromatography analysis. The recoveries of spiked seawater on the MISPE cartridges were from 83.0% to 90.6%, and the values of the relative standard deviation were in the range of 2.78-4.13% (n=3). The satisfied results showed that this pre-treatment methodology for extracting mebendazole in seawater was simple and effective.

Preparation of core–shell ion imprinted nanoparticles via photoinitiated polymerization at ambient temperature for dynamic removal of cobalt in aqueous solution

In this work, novel core–shell ion imprinted polymers were firstly synthesized by photoinitiated polymerization (P-IIPs) for the selective separation of Co(ii) in aqueous solution.

Hydrophilic molecularly imprinted microspheres functionalized with amino and carboxyl groups for highly selective recognition of human hemoglobin in aqueous solution

HMIMs functionalized with amino and carboxyl groups were synthesized for HHb. The HMIMs exhibit selective recognition properties toward the target protein. QCM results demonstrate the HMIMs coated electrode shows a more sensitive response to HHb than the NIMs coated one.

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.