Molecularly imprinted polymer for metsulfuron-methyl and its binding characteristics for sulfonylurea herbicides

Novel detection method to rapidly quantify toxic cucurbitacin in Lagenaria siceraria (bottle gourd)

Bottle gourd (Lagenaria siceraria) is widely used in India for its medicinal properties. Sometimes its consumption as a fruit or juice can lead to serious health issues due to the presence of toxic cucurbitacins (Cuc) like Cuc B at high concentration. In the present study, a molecularly imprinted polymer (MIP) based method was developed to quantify Cuc B in commercial bottle gourd juice. Cuc B quantification was also done in peel and pulp of fresh bottle gourd fruit. Developed MIP was superior to NIP (non-imprinted polymer) in terms of equilibrium binding, solid-phase extraction, selectivity, and loading capacity of Cuc B. Scatchard plot analysis, adsorption kinetics, and surface area study further strengthen the fact that prepared imprinted polymer was better than NIP for Cuc extraction. TLC and high-resolution LC-MS based analysis revealed that MIP selectively extracts Cuc B from all the studied samples. It was further observed that gamma irradiation and β-glucosidase treatment did not have any significant (p > 0.05) effect on Cuc concentration. The quantity of Cuc in 100 g of juice, peel, and pulp was 2.81 ± 0.26, 3.37 ± 0.31, and 2.39 ± 0.21 mg, respectively. Analytical method validation indicates that the MIP based method was highly linear, precise, and accurate to rapidly quantify toxic Cuc B in bottle gourd consequently assuring its quality.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05600-3.

One-pot synthesis of ion-imprinted three-dimensional porous material based on graphene oxide for the selective adsorption of copper(II)

Molecularly imprinted polymers (MIPs) are synthetic polymers with predetermined selectivity for a given analyte. One major problem associated with MIPs is the inaccessibility of a large fraction of the recognition sites that remain buried within the polymeric matrix. To address this problem, the high selectivity imparted by the imprinting technique and the porosity of three-dimensional (3D) graphene oxide (GO)-based porous materials were utilized in this work to prepare a 3D GO-based Cu(II)-ion-imprinted material (hereafter denoted as IIM) via one-pot reactions of GO, chitosan (CS), and glutaraldehyde in the presence of Cu(II). Results of equilibrium binding experiments show that IIM has a high template-ion binding capacity (1.75 mmol g^-1) and good imprinting factor (2.19). Further, results of selectivity tests indicate that IIM has a high Cu(II)-recognition ability. IIM also has a fast binding rate and satisfactory reusability. In addition, the Langmuir isotherm model was well fitted with the experimental data, indicating the monolayer adsorption of Cu(II) ions. The present work provided a convenient approach to prepare 3D GO-based imprinted materials that are promising for enrichment or recycling of target compounds from wastewater.

Green molecularly imprinted polymers for sustainable sample preparation

The use of molecularly imprinted polymers in sample preparation as selective sorbent materials has received great attention during the last years leading to analytical methods with unprecedented selectivity. However, with the progressive implementation of Green Analytical Chemistry principles, it is necessary to critically review the greenness of synthesis and further use of molecularly imprinted polymers in sample preparation. Accordingly, in the present review, the different steps and strategies for the preparation of molecularly imprinted polymers, the used reagents, as well as their incorporation to microextraction techniques are reviewed from a green perspective and recent alternatives to make the use of molecularly imprinted polymers more sustainable are provided.

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.

Magnetic molecularly imprinted polymer prepared by microwave heating for confirmatory determination of chloramphenicol in chicken feed using high-performance liquid chromatography-tandem mass spectrometry

A magnetic molecularly imprinted polymer (MMIP) for chloramphenicol was prepared using a surface-imprinted and microwave-heating-induced polymerization method. The surfaces of the magnetic particles were first double-bond functionalized with 3-(trimethoxysilyl)propyl methacrylate (γ-MPS), followed by the copolymerization of 4-vinyl pyridine (4-VP) and trimethylolpropane trimethacrylate (TRIM) in the presence of chloramphenicol as a template and 1,1-azobis(cyclohexane-carbonitrile) (ABCN) as an initiator in a mixture of dimethyl sulfoxide and water with microwave heating at 80°C. The magnetic polymer possesses supraparamagnetic properties and was used to concentrate and cleanup chicken feed extract, followed by chromatographic separation using a Lichrospher®100 RP C8 column and detection with two multi-reaction monitoring transitions at m/z 321→ 152 and m/z 321→ 257. The mean recoveries obtained at two spiking levels were in the range of 94.6-100% The relative intra- and inter-day standard deviations were in the range of 1.4-2.6% and 5.1-5.7%, respectively. The detection limit of the method was 0.12 µg kg^-1. This confirmatory method was successfully applied to determine chloramphenicol in chicken feed samples.

Enhanced photocatalytic degradation of doxycycline using a magnetic polymer-ZnO composite

A novel magnetic polymer-ZnO composite was prepared by incorporating Fe₃O₄ and ZnO nano-particles in the structure of an adsorbent polymer. Precipitation polymerization was used for synthesizing the adsorbent polymer and its efficiency for extracting doxycycline from aqueous solution was optimized according to several parameters including time, pH and amount of polymer. Results showed the highest extraction efficiency at neutral pH of the doxycycline solution in 20 min, and the capacity of the polymer was about 20 mg/g. The magnetic property of a material is important for fast and facile separation of composite particles after each use. Magnetic polymer-ZnO composite was synthesized by adding Fe₃O₄ and ZnO nano-particles to the polymerization mixture in order to take advantage of both sorption and photocatalytic degradation mechanisms. The obtained composite was characterized using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy equipped with wavelength dispersive X-ray spectroscopy and used for enhanced photocatalytic degradation of doxycycline in aqueous solution. Results showed 76.5% degradation of doxycycline in 6 hours which was significantly higher than the degradation observed by an equivalent amount of ZnO nano-particles. Photocatalytic degradation of doxycycline fitted the pseudo first order kinetic model with a rate constant of 4 × 10^-3 μg mL^-1 min^-1.

Review of Sample Preparation Techniques for the Analysis of Selected Classes of Pesticides in Plant Matrices

The aim of this article is to present the trends in extraction techniques applied for the isolation of pesticides from plant matrix. To fully compare the effectiveness of different extraction techniques, it was required to analyze compounds with possibly wide spectrum of physicochemical properties. Hence, compounds representing neonicotinoids, pyrethroids, sulfonylureas and phenylamides were selected. Based on literature studies, it may be concluded that there are three main approaches to make the analytical procedures for pesticides determination more effective: (i) the optimization of extraction conditions, however, according to ANOVA conducted on the collected literature data, not all parameters influence the extraction process equally; chemometric studies based on literature reports may lead to the conclusion that the most favorable conditions (criterion: analyte recovery, repeatability) for neonicotinoid, pyrethroid and sulfonylurea herbicide extraction from plant tissues are provided by QuEChERS - extraction with acetonitrile, while the mixtures of PSA and GCB (for neonicotinoids), and PSA, GCB, C18 (for pyrethroids) should be used in d-SPE step. For sulfonylurea compounds and metalaxyl it was impossible to identify a sorbent(s) that cleans up the extract more effectively than the others; (ii) to develop a new generation of sorbents; however, the range of their applicability is limited, mainly due to difficulties in their synthesis; (iii) to develop the new extraction techniques with as few "trouble spots" as possible.

Molecularly Imprinted Solid Phase Extraction using Bismethacryloyl-β-cyclodextrin and Methacrylic Acid as Double Functional Monomers for Selective Analysis of Glycyrrhizic Acid in Aqueous Media

In this work, a new molecularly imprinted solid phase extraction protocol was developed for the selective extraction and purification of glycyrrhizic acid from liquorice roots in aqueous media. The molecularly imprinted polymers (MIPs) for glycyrrhizic acid were prepared by using bismethacryloyl-β-cyclodextrin and methacrylic acid as double functional monomers and characterized by Fourier transform infrared spectroscopy, scanning electron microscope, thermo gravimetric analysis, nitrogen adsorption and elemental analysis. In aqueous media, the adsorption properties of MIPs including adsorption kinetics, adsorption isotherms and selectivity adsorption were investigated. The characterization of imprinted polymers indicated that the prepared MIPs had good stability and many cavity structures. The results of adsorption experiments illustrated the MIPs had high adsorption capacity of glycyrrhizic acid (69.3 mg g⁻¹) with the imprinting factor 3.77, and it took ~5 min to get adsorption equilibrium. The MIPs could be used as an solid phase extraction sorbent absorbent for enrichment and purification of glycyrrhizic acid from the crude extraction of licorice roots, and the results showed promising practical value.

Molecularly imprinted polymers as the extracted sorbents of clenbuterol ahead of liquid chromatographic determination

A pre-treatment methodology for clenbuterol hydrochloride (CLEN) isolation and enrichment in a complex matrix environment was developed through exploiting molecularly imprinted polymers (MIPs). CLEN-imprinted polymers were synthesized by the combined use of ally-β-cyclodextrin (ally-β-CD) and methacrylic acid (MAA), allyl-β-CD and acrylonitrile (AN), and allyl-β-CD and methyl methacrylate (MMA) as the binary functional monomers. MAA-linked allyl-β-CD MIPs (M-MAA) were characterized by Fourier transform-infrared (FT-IR) spectroscopy and a scanning electron microscope (SEM). Based upon the results, M-MAA polymers generally proved to be an excellent selective extraction compared to its references: AN-linked allyl-β-CD MIPs (M-AN) and MMA-linked allyl-β-CD MIPs (M-MMA). M-MAA polymers were eventually chosen to run through a molecularly imprinted solid-phase extraction (MISPE) micro-column to enrich CLEN residues spiked in pig livers. A high recovery was achieved, ranging from 91.03% to 96.76% with relative standard deviation (RSD) ≤4.45%.

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.

Synthesis of metronidazole-imprinted molecularly imprinted polymers by distillation precipitation polymerization and their use as a solid-phase adsorbent and chromatographic filler

Metronidazole-imprinted polymers with superior recognition properties were prepared by a novel strategy called distillation-precipitation polymerization. The as-obtained polymers were characterized by Fourier-transform infrared spectroscopy, laser particle size determination and scanning electron microscopy, and their binding performances were evaluated in detail by static, kinetic and dynamic rebinding tests, and Scatchard analysis. The results showed that when the fraction of the monomers was 5 vol% in the whole reaction system, the prepared polymers afforded good morphology, monodispersity, and high adsorption capacity and excellent selectivity to the target molecule, metronidazole. The optimal binding performance is 12.41 mg/g for metronidazole just before leakage occurred and 38.51 mg/g at saturation in dynamic rebinding tests. Metronidazole-imprinted polymers were further applied as packing agents in solid-phase extraction and as chromatographic filler, both of which served for the detection of metronidazole in fish tissue. The results illustrated the recoveries of spiked samples ranged from 82.97 to 87.83% by using molecularly imprinted solid-phase extraction combined with a C18 commercial column and 93.7 to 101.2% by directly using the polymer-packed chromatographic column. The relative standard deviation of both methods was less than 6%.

A simple approach to prepare molecularly imprinted polymers from nylon-6

A convenient and simple approach for the preparation of molecularly imprinted polymers (MIPs) based on polyamide (nylon-6) was developed. The polymer matrix formation occurred during the transition of nylon from dissolved to solid state in the presence of template molecules in the initial solution. 2,2,2-Trifluoroethanol (TFE) was chosen as a main solvent for the polyamide. It provides a high solubility of nylon and does not significantly change the structure of biopolymers. The alteration of the polymer matrix structure after the addition of different types of porogens in the nylon/TFE solution was investigated. The structured polymers in the form of films and microparticles were prepared in the chosen optimal conditions. Different model biomolecular templates (of low- and high-molecular weight) were used for the preparation of MIPs, which were shown to specifically recognize these molecules upon binding experiments. The binding of the template molecules to MIPs was monitored using spectrophotometric, radioisotopic, or fluorometric detection. The selectivity coefficients of the MIPs were estimated to be 1.4-4.6 depending on the type of templates and conditions of the polymer matrix formation.

Preparation of magnetic molecularly imprinted polymer for selective recognition of resveratrol in wine

The magnetic molecularly imprinted polymers (MMIPs) for resveratrol were prepared by using surface molecular imprinting technique with a super paramagnetic core-shell nanoparticle as a supporter. Rhapontigenin, which is the analogues of resveratrol, was selected as dummy template molecules to avoid the leakage of trace amount of resveratrol. Acrylamide and ethylene glycol dimethacrylate were chosen as functional monomers and cross-linker, respectively. The obtained MMIPs were characterized by using scanning electron microscopy, Fourier transform infrared spectrum, X-ray diffraction and vibrating sample magnetometer. High performance liquid chromatography was used to analyze the target analytes. The resulting MMIPs exhibited high saturation magnetization of 53.14emug(-1) leading to the fast separation. The adsorption test showed that the MMIPs had high adsorption capacity for resveratrol and contained homogeneous binding sites. The MMIPs were employed as adsorbent of solid phase extraction for determination of resveratrol in real wine samples, and the recoveries of spiked samples ranged from 79.3% to 90.6% with the limit of detection of 4.42ngmL(-1). The prepared MMIPs could be employed to selectively pre-concentrate and determine resveratrol from wine samples.

Selective separation of deltamethrin by molecularly imprinted polymers using a β-cyclodextrin derivative as the functional monomer

A deltamethrin-imprinted polymer (MIP(1)) was prepared using bis(-6-O-butanediacid monoester)-β-cyclodextrin (BBA-β-CD) as the functional monomer and toluene 2,4-diisocyanate (TDI) as the cross-linker. In comparison to the molecularly imprinted polymer where β-CD was applied as the functional monomer (MIP(2)), MIP(1) showed a higher specific binding capacity (ΔC(P)) and an improved imprinting factor (IF) for deltamethrin. The selective recognition experiments demonstrated that compared to MIP(2), MIP(1) could better recognize its template over other substrates that had similar chemical structures. The solid phase extraction (SPE) of deltamethrin using MIP(1) as the adsorbent was further investigated. The recoveries of the molecularly imprinted solid phase extraction (MISPE) column for deltamethrin were 83.2-93.4% with relative standard deviations (RSD) of 2.03-6.19%. The method has been successfully applied to the enrichment of trace deltamethrin from real water samples.

Competitive sorption of metsulfuron-methyl and tetracycline on corn straw biochars

The application of biochars into soil may influence the fate of contaminants. Sorption and competitive sorption of metsulfuron-methyl (ME) and tetracycline (TC) on corn straw biochars prepared at 100 to 600°C (referred to as CS100-CS600) were examined. The Freundlich model described sorption isotherms well. The lower sorption capacity () of ME compared with TC on the biochars was attributed to the electrostatic repulsion between the anionic ME and the negatively charged biochars. No electrostatic repulsion between the zwitterionic TC and the biochars occurred. Tetracycline exhibited little competition with ME for CS100-CS300 in bi-solute systems, suggesting that partitioning of ME into noncarbonized rubbery organic matter might be the dominant sorption mechanism. The nonlinear isotherms of ME on CS400-CS600 and those of TC on CS100-CS600 suggested adsorption as the dominant mechanism. A significant increase in the Freundlich values in the bi-solute systems might be attributed to TC/ME occupying and blocking ME/TC-specific adsorption sites. The percentage decreases in of TC on CS400-CS600 with low ME concentrations were lower than those on CS200-CS300. This might be attributed to the lower steric restriction of ME for TC on CS400-CS600 because of their larger specific surface areas. The larger percentage decrease in of ME with TC from CS400 to CS600 may be explained by a decrease in the hydrophobicity and the increased sorption of TC with numerous polar groups. When using biochars as engineered sorbents to prevent the transport of ME from soil, the effect of coexisting TC needs to be taken into account.

Study of the molecularly imprinted polymers for selective binding of the mono-substituted sulfonylurea herbicides

A new molecularly imprinted polymer (MIP) was synthesized for the selective extraction of mono-substituted sulfonylurea herbicides, with monosulfuron as the template and acrylamide as the functional monomer. The recognition property and affinity of the MIP for monosulfuron and its analog, monosulfuron-ester, were evaluated by equilibrium adsorption and a chromatographic study. Computer modeling, including simulated annealing and semi-empirical quantum calculation, was employed to study the recognition mechanism. The computer modeling demonstrated that monosulfuron can form multiple hydrogen bonds with methacrylic acid and acrylamide, whereas monosulfuron-ester cannot form a stable complex with these two functional monomers, which aligns with the results of the rebinding experiment. The selectivity study further demonstrated that binding sites in the MIP interact with the hydrogen in the acylamino group of mono-substituted sulfonylurea. A comparison experiment also showed that monosulfuron-imprinted MIP offers better selectivity for monosulfuron-ester than the commercial C18 high-performance liquid chromatography stationary phase material.