Molecularly imprinted polymer coated on stainless steel fiber for solid-phase microextraction of chloroacetanilide herbicides in soybean and corn

A novel green molecularly imprinted polymers synthesized in an aqueous medium as S-metolachlor sensitive materials

A new molecularly imprinted polymer (MIP) sensitive and selective for S-metolachlor herbicide was synthesized by bulk polymerization with the use of N-isopropylacrylamide, acrylamide, and acrylic acid as functional monomers, and N,N'- methylenebis(acrylamide) as a cross-linker. A novel method for obtaining MIP toward S-metolachlor in an aqueous medium and at room temperature, according to the principles of green chemistry, has been discovered, in comparison to synthesis methods at high temperatures and using organic solvents. Under selected experimental conditions, the batch mode type of sorption was carried out efficiently, with S-metolachlor absorption of 2.4 mg per 1 g of MIP and 0.5 mg per 1 g of NIP. The selectivity of the sorbent towards other herbicides and pesticides was also tested, obtaining an ability to recognize S-metolachlor molecules 3.2 times better than atrazine, 6 times better than glyphosate, and 6.2 times better than fenoxaprop-P-ethyl. The FT-IR and SEM analyses were performed to characterize the structure of the synthesized polymers.

Synthesis of MIL-88(Fe) coordinated to carboxymethyl cellulose fibers nanocomposite for dispersive solid phase microextraction of acetanilide herbicides from cereal and agricultural soil samples

In this study, MIL-88(Fe) coordinated to carboxymethyl cellulose fibers was successfully synthesized, characterized, and utilized as a nanocomposite for the dispersive solid phase microextraction of butachlor and acetochlor. These analytes served as representative analytes for acetanilide herbicides (AHs) present in real samples. Effective parameters on the extraction efficiency were investigated to maximize the analytical performance of the developed method. Under optimized conditions, which encompassed sorbent amount of 12 mg, solution pH of 7.0, 4.0 min of the vortex time, 3.0 min of the extraction time, chloroform as desorption agent and no salt addition, the developed method exhibited remarkable figures of merit, such as high linearity (R2> 0.99), low limits of detection of 0.90 ng mL-1, substantial preconcentration factors (between 213 and 228), relative recoveries in the range of 90.8% to 109%, and good repeatability with relative standard deviations equal or below 7.2%. After validation, the developed method was applied to detect AHs in various cereal and agricultural soil samples.

Cellular toxicity and pharmacokinetic study of butachlor by ultra-performance liquid chromatography-tandem mass spectrometry based on tandem mass spectrometry cubed technique

Butachlor is an aromatic amide compound that plays a role as a herbicide, a xenobiotic, and an environmental contaminant. The aim of this work was to develop a highly selective and sensitive ultra-performance liquid chromatography-tandem mass spectrometry method based on the tandem mass spectrometry cubed technique to determine butachlor in a biological matrix. Butachlor and internal standard acetochlor were separated on a Waters Acquity ultra-performance liquid chromatography BEH C₁₈ column (2.1 × 50 mm, 1.7 μm) with gradient elution using 0.1% formic acid aqueous solution (A) and acetonitrile (B) as mobile phases. The transitions selected for tandem mass spectrometry cubed quantitative analysis in positive ion mode were: for butachlor, mass-to-charge ratio 312.2→238.1→162.1; for acetochlor, mass-to-charge ratio 270.1→224.0→148.1. The total running time for each sample was 5.5 min. The ultra-performance liquid chromatography-tandem mass spectrometry cubed method showed a linear relationship (R² ≥ 0.995) in the concentration range of 0.5-100 ng/ml. The intra and interday accuracies are within the range of -10.6%-4.3% and precisions are between 4.48% and 13.14%. The novelty of the method is the use of tandem mass spectrometry cubed scanning mode, which improves selectivity and sensitivity. The results indicated that butachlor was cellular toxic. The safety of butachlor should be considered when it is used as a herbicide.

A dispersive solid phase extraction adsorbent based on aptamer modified chitosan nanofibers for zearalenone separation in corn, wheat, and beer samples

Highly selective separation of trace bio-toxins in food samples has long been a hot topic pursued by analytical chemists. In this paper, chitosan nanofibers prepared by freeze-drying were modified with aptamers for dispersive solid phase extraction (dSPE) of trace zearalenone. The morphology of achieved chitosan nanofibers was found to be uniform and continuous, and the length was at the micron level with about a 400 nm diameter. The immobilization capacity of the aptamer was as high as 10.1 μg on 5 mg chitosan nanofibers with good stability and repeatability, owing to the high specific surface area of nanofibers. The aptamer modified chitosan nanofibers (Apt-CNFs) showed specific selectivity to zearalenone with a selectivity coefficient of 2.65 compared to the scrambled oligonucleotide functionalized CNFs, and the selectivity factors over other analogs and reference compounds were from 1.57 to 50.0. After the optimization of extraction conditions, the Apt-CNF based dSPE was coupled with high-performance liquid chromatography for zearalenone monitoring, and a good linear range of 0.06-10.0 μg L-1 was achieved with a detection limit of 18.0 ng L-1. The spiking recoveries of 101-108%, 100-110%, and 98.3-101% were achieved for trace zearalenone in corn, wheat, and beer samples, respectively. The residual zearalenone was detected in corn and wheat with a content of 0.365 and 0.0775 μg g-1, respectively.

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.

Fabrication of a porous β-cyclodextrin-polymer-coated solid-phase microextraction fiber for the simultaneous determination of five contaminants in water using gas chromatography-mass spectrometry

A novel solid-phase microextraction fiber coated with a porous β-cyclodextrin polymer was developed. The porous β-cyclodextrin polymer cross-linked using tetrafluoroterephthalonitrile, possessed well-distributed pores and the largest surface area among current β-cyclodextrin polymers. Scanning electron microscopy revealed that the coating had a continuous wrinkled and folded structure, which guarantees a sufficient loading capacity for contaminants. The properties of the developed fiber were evaluated using headspace solid-phase microextraction of five contaminants as model analytes coupled with gas chromatography-mass spectrometry. Owing to the advantages of a large surface area and three-dimensional cavities, the novel fiber exhibited excellent operational stability and extraction ability. After optimisation of the extraction conditions, including extraction temperature, extraction time, salt effect, and desorption time, validation of the method with water samples achieved good linearity over a wide range (0.01–120 μg L⁻¹) and low detection limits (0.003–1.600 μg L⁻¹). The single-fiber and fiber-to-fiber repeatabilities were 1.7–11.0% and 1.9–11.0%, respectively. The method was applied to the simultaneous analysis of five analytes with satisfactory recoveries (76.6–106.0% for pond water and 89.0–105.9% for rainwater).

A novel solid-phase microextraction fiber coated with a porous β-cyclodextrin polymer was developed.

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.

Bifunctional monomer molecularly imprinted polymers based on the surface of multiwalled carbon nanotubes for solid-phase extraction of tartrazine from drinks

A novel bifunctional monomer MIP with an improved selectivity for tartrazine on the surface of MWNTs was synthesised.

Enantioselective and Synergetic Toxicity of Axial Chiral Herbicide Propisochlor to SP2/0 Myeloma Cells

The axial chiral herbicide propisochlor is used to control weeds. Different enantiomers of a compound usually have different biological activities. It is unclear how the toxicities of the propisochlor enantiomers differ. Propisochlor enantiomers, separated by high-performance liquid chromatography, were tested on SP2/0 myeloma cells. Cytotoxicity and apoptosis were measured, and interactions between the enantiomers were evaluated. The rac-propisochlor, pure R-(+) isomer, and pure S-(-) isomer inhibited cell proliferation and induced apoptosis. The rac-propisochlor, R-(+) isomer, and S-(-) isomer half maximal effective concentration values after 24 h of incubation were 111 ± 0.15, 68 ± 0.09, and 99 ± 0.21 μM, respectively. R-(+) isomer induced the most apoptosis. R-(+) isomer was ∼1.63 times more cytotoxic than rac-propisochlor and ∼1.46 times more cytotoxic than S-(-) isomer. Antagonistic cytotoxic interactions were found between R-(+) and S-(-) isomers. This is the first time the toxicities of these enantiomers and antagonism between the enantiomers have been reported. The antagonism indicates that the ecotoxicological effects of the enantiomers should be investigated.

Preparation of temperature sensitive molecularly imprinted polymer coatings on nickel foam for determination of ofloxacin in Yellow River water by solid-phase microextraction

A new ofloxacin-templated MIP on nickel foam was investigated for the determination of antibiotics in river water.

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.

Preparation and selective recognition of a novel solid-phase microextraction fiber combined with molecularly imprinted polymers for the extraction of parabens in soy sample

A prepared molecularly imprinted polymer with ethyl p-hydroxybenzoate as template molecule was applied for the first time to a homemade solid-phase microextraction fiber. The molecularly imprinted polymer-coated solid-phase microextraction fiber was characterized by scanning electron microscopy and thermogravimetric analysis. Various parameters were investigated, including extraction temperature, extraction time, and desorption time. Under the optimum extraction conditions, the molecularly imprinted polymer-coated solid-phase microextraction fiber exhibited higher selectivity with greater extraction capacity toward parabens compared with the nonimprinted polymer-coated solid-phase microextraction fiber and commercial fibers. The molecularly imprinted polymer-coated solid-phase microextraction fiber was tested using gas chromatography to determine parabens, including methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, and propyl p-hydroxybenzoate. The linear ranges were 0.01-10 μg/mL with a correlation coefficient above 0.9943. The detection limits (under signal-to-noise ratio of 3) were below 0.30 μg/L. The fiber was successfully applied to the simultaneous analysis of three parabens in spiked soy samples with satisfactory recoveries of 95.48, 97.86, and 92.17%, respectively. The relative standard deviations (n=6) were within 2.83-3.91%. The proposed molecularly imprinted polymer-coated solid-phase microextraction method is suitable for selective extraction and determination of trace parabens in food samples.

Preparation of an ion-imprinted fiber for the selective removal of Cu2+

A novel Cu(2+)-imprinted fiber (IIF) was prepared by grafting acrylic acid (AA) onto the surface of a polypropylene (PP) fiber and subsequently modified with polyethylenimine (PEI). An examination by infrared spectroscopy and scanning electron microscopy confirmed that the ion-imprinted polymer was successfully introduced onto the surface of a PP fiber. The modification of PP fibers with AA was beneficial to the grafting of PEI onto the fibers. The highest grafting degree of PEI could reach 120 wt % under optimal grafting conditions. This IIF showed excellent tensile and chemical stability in acid solution, which qualified the IIF for practical applications. Besides having a high adsorption capacity for Cu(2+) (120 mg/g), the IIF adsorbent showed a high selectivity for Cu(2+) as compared with that of the non-ion-imprinted fiber (NIF). The dynamic adsorption results indicated that IIF can thoroughly remove Cu(2+) from the solution in a relatively short contact time. The effective treatment volume was about 910 bed volumes. The selectivity coefficient of IIF for Cu(2+) with respect to Zn(2+) could reach 76.4. IIF also has good regeneration performance and could maintain almost the same adsorption capacity for copper ions after 10 adsorption-desorption cycles.