Development of magnetic molecularly imprinted polymers based on carbon nanotubes - application for trace analysis of pyrethroids in fruit matrices

Green preparation of magnetic porous carbon by high value utilization of metallurgical waste liquid for efficient extraction of pesticide residues in the environment

Metal-organic frameworks were prepared from Fe-containing waste liquid generated during the refining process of nickel metallurgical slag as a metal source, providing a green treatment method for industrial waste liquid. The Fe-containing waste liquid was used as a raw material for the coordination synthesis of MIL-100(Fe) with 1,3,5-benzenetricarboxylic acid, whereas the ionic liquid-modified magnetic porous carbon material (Fe3O4@C/[BMIM]PF6) was prepared by loading [BMIM]PF6 into the pore size of Fe3O4@C obtained by carbonization derivatization. Since Fe3O4@C/[BMIM]PF6 exhibits strong hydrophobicity and contains unsaturated functional groups as well as hydrogen bond acceptors in structure, and a large pore size, it was used as a highly efficient adsorbent for the extraction of trace pyrethroid insecticides in the environment. Fe3O4@C/[BMIM]PF6 demonstrated excellent extraction ability, and the recoveries of the four pyrethroid insecticides in the actual samples analyzed ranged from 85.75 to 112.13%. Fe3O4@C/[BMIM]PF6 has excellent reusability and batch-to-batch reproducibility, and the relative standard deviations for the extraction recoveries of pyrethroids insecticides from the five batches were 2.14%-3.65%. The MIL-100(Fe) synthesized from high-volume preparation experiments exhibited excellent physical/chemical properties. Therefore, the green prepared Fe3O4@C/[BMIM]PF6 based on waste liquid has excellent extraction properties, and the study provides a green and low-energy treatment method for waste liquids generated by metallurgy.

High selectivity molecularly imprinted polymer based on short amylose as bio-based functional monomers for selective extraction of λ-cyhalothrin

Nowadays, the development of sustainable molecularly imprinted polymers (MIPs) with high selectivity is still challenging due to the limitations of bio-based functional monomers. In this study, the highly selective and porous MIPs (LC-TMIPs) were designed and prepared on short amylose (SAM) as bio-based functional monomers, λ-cyhalothrin (LC) as a template molecule, and tetrafluoroterephthalonitrile as a rigid crosslinking agent. Static, dynamic, and selective adsorption experiments were conducted to investigate the adsorption performance. The results indicated that, compared to MIPs prepared using epichlorohydrin as flexible crosslinking agents, LC-TMIPs exhibited higher imprinting factor (3.93), selectivity (5.78), and adsorption capacity (35.79 mg g-1), as well as faster adsorption/desorption kinetics. The LC-TMIPs were used as sorbents for the selective determination of LC in both apple and cucumber samples by high-performance liquid chromatography. Under the optimal extraction conditions, the recoveries of the method reached 92.1-106.1 %, with a linear range of 1.5-30 ng g-1 and a detection limit of 0.5 ng g-1. The proposed preparation method of LC-TMIPs is expected to open a new way to prepare highly selective and sustainable MIPs for hydrophobic compounds.

Assessing the greenification potential of cyclodextrin-based molecularly imprinted polymers for pesticides detection

Cyclodextrins, with their unparalleled attributes of eco-friendliness, natural abundance, versatile utility, and facile functionalization, make a paramount contribution to the field of molecular imprinting. Leveraging the unique properties of cyclodextrins in molecularly imprinted polymers synthesis has revolutionized the performance of molecularly imprinted polymers, resulting in enhanced adsorption selectivity, capacity, and rapid extraction of pesticides, while also circumventing conventional limitations. As the concern for food quality and safety continues to grow, the need for standard analytical methods to detect pesticides in food and environmental samples has become paramount. Cyclodextrins, being non-toxic and biodegradable, present an attractive option for greener reagents in imprinting polymers that can also ensure environmental safety post-application. This review provides a comprehensive summary of the significance of cyclodextrins in molecular imprinting for pesticide detection in food and environmental samples. The recent advancements in the synthesis and application of molecularly imprinted polymers using cyclodextrins have been critically analyzed. Furthermore, the current limitations have been meticulously examined, and potential opportunities for greenification with cyclodextrin applications in this field have been discussed. By harnessing the advantages of cyclodextrins in molecular imprinting, it is possible to develop highly selective and efficient methods for detecting pesticides in food and environmental samples while also addressing the challenges of sustainability and environmental impact.

A Schiff base networks coated stir bar for sorptive extraction of pyrethroid pesticide residues in tobacco

Schiff base networks (SNWs) were introduced as a new stir bar coating, and a method of SNWs- coated stir bar sorptive extraction (SBSE) coupled to high performance liquid chromatography-ultraviolet detector (HPLC-UV) was developed for determination of pyrethroid pesticide residues in tobacco. The prepared amorphous SNWs polymer from melamine and 3,5-dihydroxybenzaldehyde riches in triazine rings, hydroxyl groups and amino groups, and the SNWs/polydimethylsiloxane (PDMS) stir bar prepared by sol-gel method can extract weakly polar pyrethroid pesticides through hydrophobic, π-π and hydrogen bonding. The SNWs/PDMS stir bar exhibited high extraction efficiency toward pyrethroid pesticides (70-76%) and good mechanical stability with reused time more than 50 times. Under the optimal experimental conditions, the limits of detection were 0.20 - 0.66 µg/L with relative standard deviation varying in the range of 2.3-8.2%, which meets the requirements of trace analysis of pesticide residues in the tobacco industry. The method was applied to the determination of six pyrethroid pesticides in cigarette samples, and the recovery for the spiked samples ranged from 82 to 117%, showing a great applicability for the analysis of pesticide residues in real samples with a complex sample matrix.

A review on recent advances in the applications of composite Fe3O4 magnetic nanoparticles in the food industry

Fe3O4 magnetic nanoparticles (MNPs) have attracted tremendous attention due to their superparamagnetic properties, large specific surface area, high biocompatibility, non-toxicity, large-scale production, and recyclability. More importantly, numerous hydroxyl groups (-OH) on the surface of Fe3O4 MNPs can provide coupling sites for various modifiers, forming versatile nanocomposites for applications in the energy, biomedicine, and environmental fields. With the development of science and technology, the potential of nanotechnology in the food industry has also gradually become prominent. However, the application of composite Fe3O4 MNPs in the food industry has not been systematically summarized. Herein, this article reviews composite Fe3O4 MNPs, including their properties, modifications, and physical functions, as well as their applications in the entire food industry from production to processing, storage, and detection. This review lays a solid foundation for promoting food innovation and improving food quality and safety.

Application, advancement and green aspects of magnetic molecularly imprinted polymers in pesticide residue detection

Molecularly imprinted polymers (MIPs) have added a vital contribution to food quality and safety with the effective extraction of pesticide residues due to their unique properties. Magnetic molecularly imprinted polymers (MMIPs) are a superior approach to overcome stereotypical limitations due to their unique core-shell and novel composite structure, including high chemothermal stability, rapid extraction, and high selectivity. Over the past two decades, different MMIPs have been developed for pesticide extraction in actual food samples with a complex matrix. Nevertheless, such developments are desirable, yet the synthesis and mode of application of MMIP have great potential as a green chemistry approach that can significantly reduce environmental pollution and minimize resource utilization. In this review, the MMIP application for single or multipesticide detection has been summarized by critiquing each method's uniqueness and efficiency in real sample analysis and providing a possible green chemistry exploration procedure for MMIP synthesis and application for escalated food and environmental safety.

In situ fabrication of nitrogen doped graphitic carbon networks coating for high-performance extraction of pyrethroid pesticides

The tailor-prepare solid phase microextraction (SPME) coatings with stable and excellent properties to effectively extract analytes from sample matrix still remains a challenge. Herein, a nitrogen doped graphitic carbon networks (NG-CNTW) coated fiber was fabricated by direct carbonization of nanosized ZIF-67 crystals (nano-ZIF-67) that grown on stainless steel wire. The NG-CNTW coated fiber coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS) was applied for enrichment and determination of pyrethroids. The NG-CNTW coating exhibited high surface area and hierarchical porous structures that facilitate diffusion and accessibility of target molecules. Simultaneously, the nitrogen doped and highly graphitic structures endow the coating with high adsorption affinity for aromatic compounds. Under optimum conditions, the SPME-GC-MS/MS method presented wide range of linearity performance (0.08-200.0 ng g^-1), low limits of detection (0.02-0.5 ng g^-1) and good repeatability (RSD < 9.6%) for 8 kinds of pyrethroids. Furthermore, the proposed method was successfully applied in the determination of pyrethroids in grape and cauliflower samples, as the results were in the range of 3.16-15.06 ng g^-1and 2.08-9.29 ng g^-1, respectively. This work not only provides a new method by fabricating carbon nanomaterial coatings in situ derived from MOFs, but also shows great potential of MOFs derivative materials in environmental analysis field.

Molecularly Imprinted Polymers for Dispersive (Micro)Solid Phase Extraction: A Review

The review describes the development of batch solid phase extraction procedures based on dispersive (micro)solid phase extraction with molecularly imprinted polymers (MIPs) and magnetic MIPs (MMIPs). Advantages and disadvantages of the various MIPs for dispersive solid phase extraction and dispersive (micro)solid phase extraction are discussed. In addition, an effort has also been made to condense the information regarding MMIPs since there are a great variety of supports (magnetite and magnetite composites with carbon nanotubes, graphene oxide, or organic metal framework) and magnetite surface functionalization mechanisms for enhancing MIP synthesis, including reversible addition-fragmentation chain-transfer (RAFT) polymerization. Finally, drawbacks and future prospects for improving molecularly imprinted (micro)solid phase extraction (MIMSPE) are also appraised.

Molecularly Imprinted Polymer Micro- and Nano-Particles. A review

In recent years, molecularly imprinted polymers (MIPs) have become an excellent solution to the selective and sensitive determination of target molecules in complex matrices where other similar and relative structural compounds could coexist. Although MIPs show the inherent properties of the polymers, including stability, robustness, and easy/cheap synthesis, some of their characteristics can be enhanced, or new functionalities can be obtained when nanoparticles are incorporated in their polymeric structure. The great variety of nanoparticles available significantly increase the possibility of finding the adequate design of nanostructured MIP for each analytical problem. Moreover, different structures (i.e., monolithic solids or MIPs micro/nanoparticles) can be produced depending on the used synthesis approach. This review aims to summarize and describe the most recent and innovative strategies since 2015, based on the combination of MIPs with nanoparticles. The role of the nanoparticles in the polymerization, as well as in the imprinting and adsorption efficiency, is also discussed through the review.

Quick and Sensitive Enantioselective Determination of Permethrin in Fruits and Vegetables by Combining Supramolecular Solvents and Chiral Liquid Chromatography-Tandem Mass Spectrometry

Permethrin (PM) is one of the chiral insecticides most widely used around the world. The significant differential toxicity of its four enantiomers and its important adverse effects on human health highlights the need for determination of PM enantiomers. The aim of this work was to develop the first enantioselective method for quantification of PM in fruits and vegetables. The method is based on the extraction of PM enantiomers in supramolecular solvents with restricted access properties (SUPRAS-RAM) and their separation/detection by chiral liquid chromatography-tandem mass spectrometry (LC-MS/MS) which is first reported in this article. SUPRAS-RAM-based extraction is proposed as an innovative treatment approach that drastically reduces solvent consumption and avoids the need for sample cleanup. Extraction of PM enantiomers is quick (vortexing for 5 min) and efficient (recoveries 93-107%). The method is sensitive (quantification limits from 1.0 to 1.2 μg kg^-1) and suitable for control of PM enantiomers in agri-food products.

Effective preparation of magnetic molecularly imprinted polymer nanoparticle for the rapid and selective extraction of cyfluthrin from honeysuckle

Cyfluthrin is a widely used pesticide. In this study, a sensitive and efficient magnetic molecularly imprinted polymer (MMIP) was prepared by surface molecular imprinting, which used functionalized Fe₃O₄ particles as magnetic cores. Cyfluthrin was extracted and enriched using magnetic molecularly polymer for analyzing pesticide residue of Chinese herbal medicines. The crystal type, microstructure, particle size, saturation magnetization, and characteristic functional groups of the synthesized MMIPs were analyzed by analysis equipment. The results of isothermal adsorption and kinetic adsorption indicated that MMIPs reached adsorption equilibrium at 30 min, with a maximum capacity of 4.9 mg g^-1, which had good adsorption performance, while selective adsorption experiments showed that MMIPs had higher affinity for cyfluthrin. Under the optimized conditions, the limit of detection (LOD) and the limit of quantification (LOQ) were 32.987 ng ml^-1 and 109.955 ng ml^-1, respectively. And linear range (30-3000ng ml^-1) of cyfluthrin with correlation coefficient R²=0.9979, and MMIPs were used in honeysuckle, the recoveries were 91.5%∼97.2%, and RSD was 5.35%∼8.32% (n = 3). It is indicated that the magnetic molecularly imprinted polymer can be used as an effective material for the specific separation of cyfluthrin from honeysuckle.

A microtitre chemiluminescence sensor for detection of pyrethroids based on dual-dummy-template molecularly imprinted polymer and computational simulation

The residues of pyrethroids in foods of animal origin are dangerous to the consumers, so this study presented a chemiluminescence sensor for determination of pyrethroids in chicken samples. A dual-dummy-template molecularly imprinted polymer capable of recognizing 10 pyrethroids was synthesized. The results of computation simulation showed that the specific 3D conformations of the templates had important influences on the polymer' recognition ability. The polymer was used to prepare a sensor on conventional 96-well microplates, and the sample solution was added into the wells for direct absorption. The absorbed analytes were initiated with the bis(2,4,6-trichlorophenyl)oxalate-H₂ O₂ -imidazole system, and the chemiluminescence intensity was used for analyte quantification. Results showed that one assay was finished within 12 min, and this sensor could be reused four times. The limits of detection for the 10 analytes were in the range o0.3-6.0 pg/ml, and the recoveries from the standards of fortified blank chicken samples were in the range 70.5-99.7%.

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.

Highly sensitive and selective method for the rapid determination and preconcentration of haloperidol by using a magnetite-molecularly imprinted polymer

A sensitive and selective method based on the determination of haloperidol with the usage of magnetite-molecularly imprinted polymer and high-resolution liquid chromatography has been developed. This novel method is rapid as the detection procedure for haloperidol can be completed within a total time of 1 h. The same imprinted polymer can be used for the determination of haloperidol at least 20 times. The proposed method has been succesfully applied to synthetic urine and serum samples and the recoveries of the spiked samples were in the range of 94.7-100.7%. The limit of detection and limit of quantification of the method were 2.25 and 7.50 μg/L, respectively. Linearity of the calibration graph was observed within the range of 10-250 μg/L. By combining the high capacity, high selectivity, and reusability of the magnetic adsorbent with the dynamic calibration range, high sensitivity and high resolution of liquid chromatography with quadrupole time-of-flight mass spectrometry, the proposed method is an ideal method for the determination and preconcentration of trace levels of haloperidol. A magnetite-molecularly imprinted polymer has been used for the first time as a selective adsorbent for the determination of haloperidol.

Magnetic mesoporous nanoparticles modified with poly(ionic liquids) with multi-functional groups for enrichment and determination of pyrethroid residues in apples

Considering that the determination of pyrethroid residues is of value for the safety of food, a new poly(ionic liquid)-functionalized magnetic mesoporous nanoparticle was designed and used as an adsorbent in magnetic solid-phase extraction for the enrichment of eight pyrethroids. The porous structure and large surface area of the mesoporous silica shell endow the adsorbent with abundant binding sites. In contrast to the reported poly(ionic liquids) with only one kind of functional group in the cationic part, the new poly(ionic liquids) with mixed cyano and phenyl groups in cationic part matched the chemical structure of the analytes to improve extraction efficiency. Under the optimum conditions, an effective method was established for the determination of eight pyrethroids in apples. Adsorption equilibrium can be quickly reached in 1 min, greatly decreasing the extraction time. The linearity range was found to be 10-200 ng/g, and the detection limits ranged from 0.24 to 1.99 ng/g. Recoveries of analytes in apple samples ranged from 87.3 to 119.0%, with relative standard deviations varying in the range of 3-21.2% (intraday) and 0.3-15.2% (interday). The results indicate that the proposed method is a good candidate for pyrethroid residues in apple samples.

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.

A molecularly imprinted polymer coupled with high-performance liquid chromatography-UV for the determination of albendazole in plasma and urine samples: CCD-RSM design

The present study attempted to develop a fast and sensitive ultrasound-assisted-dispersive-micro-solid phase extraction method for the separation and preconcentration of albendazole from plasma and urine samples.

Selective removal and preconcentration of triclosan using a water-compatible imprinted nano-magnetic chitosan particles

A water-compatible magnetic triclosan (TCS) imprinted material (TCS-CTS-Fe⁰-MIPs) was synthesized for selective enrichment and detection of TCS in real complex water samples. The material was synthesized by using chitosan (CTS) as functional monomer, which has rich surface O- and N-containing functional groups. The TCS imprinted CTS was coated on Fe⁰ surface and then cross-linked with glutaraldehyde. Scanning electron microscopy suggested that the imprinted material was covered with a layer of imprinted film, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed that the imprinted material had more functional groups (amino and hydroxyl groups) than that of non-imprinted material. The TCS imprinted and non-imprinted materials used in each adsorption experiments were 0.1 mg mL^-1. The maximum adsorption capacity of the TCS imprinted material and non-TCS imprinted material were 20.86 and 15.11 mg g^-1, respectively. The adsorption results showed that selectivity coefficient was 10.151, 1.353, and 8.271 in the presence of p-chlorophenol, 2,4,6-trichlorophenol, and bisphenol-A, respectively. The recoveries of river water and lake water samples were 92.8, 91.3, 92.4, and 81.4, 82.3, 82.1%, respectively, when the samples were spiked with 4, 6, and 8 μg L^-1 of TCS with the imprinted material. The adsorption capacity of the TCS imprinted material and non-TCS imprinted material lost 5.2 and 6.2% after six times of recycling. The high selectivity and excellent adsorption capacity of the imprinted material can be attributed to the presence of sterically complementary imprinted sites and high surface, which would also made it more accessible to TCS than that of non-imprinted material. The present study would provide an environmental friendly and convenient method for the removal and the monitoring of TCS in environmental water samples.

Selective and sensitive fluorimetric determination of carbendazim in apple and orange after preconcentration with magnetite-molecularly imprinted polymer

In this study, magnetite-molecularly imprinted polymer has been used for the first time as selective adsorbent before the fluorimetric determination of carbendazim. Adsorption capacity of the magnetite-molecularly imprinted polymer was found to be 2.31±0.63mgg^-1 (n=3). Limit of detection (LOD) and limit of quantification (LOQ) of the method were found to be 2.3 and 7.8μgL^-1, respectively. Calibration graph was linear in the range of 10-1000μgL^-1. Rapidity is an important advantage of the method where re-binding and recovery processes of carbendazim can be completed within an hour. The same imprinted polymer can be used for the determination of carbendazim without any capacity loss repeatedly for at least ten times. Proposed method has been successfully applied to determine carbendazim residues in apple and orange, where the recoveries of the spiked samples were found to be in the range of 95.7-103%. Characterization of the adsorbent and the effects of some potential interferences were also evaluated. With the reasonably high capacity and reusability of the adsorbent, dynamic calibration range, rapidity, simplicity, cost-effectiveness and with suitable LOD and LOQ, the proposed method is an ideal method for the determination of carbendazim.

Innovative method for the enrichment of high-polarity bioactive molecules present at low concentrations in complex matrices

Ginsenoside Rg1 is a valuable bioactive molecule but its high polarity and low concentration in complex mixtures makes it a challenge to separate Ginsenoside Rg1 from other saponins with similar structures, resulting in low extraction efficiency. The successful development of effective Rg1 molecularly imprinted polymers that exhibit high selectivity and adsorption may offer an improved method for the enrichment of active compounds. In this work, molecularly imprinted polymers were prepared with two different methods, precipitation polymerization or surface imprinted polymerization. Comparison of the adsorption abilities showed higher adsorption of the surface molecularly imprinted polymers prepared by surface imprinted polymerization, 46.80 mg/g, compared to the 27.74 mg/g observed for the molecularly imprinted polymers prepared by precipitation polymerization. Therefore, for higher adsorption of the highly polar Rg1, surface imprinted polymerization is a superior technique to make Rg1 molecularly imprinted polymers. The prepared surface molecularly imprinted polymers were tested as a solid-phase extraction column to directionally enrich Rg1 and its analogues from ginseng tea and total ginseng extracts. The column with surface molecularly imprinted polymers showed higher enrichment efficiency and better selectivity than a C₁₈ solid-phase extraction column. Overall, a new, innovative method was developed to efficiently enrich high-polarity bioactive molecules present at low concentrations in complex matrices.

Magnetic molecularly imprinted polymers–silver nanoparticle based micro-solid phase extraction for the determination of polycyclic aromatic hydrocarbons in water samples

In this study, an efficient and sensitive magnetic molecularly imprinted polymer–silver nanoparticle (MMIPS) system was successfully synthesized.

Optical detection of λ-cyhalothrin by core-shell fluorescent molecularly imprinted polymers in Chinese spirits

In this study, fluorescent molecularly imprinted polymers (FMIPs), which were for the selective recognition and fluorescence detection of λ-cyhalothrin (LC), were synthesized via fluorescein 5(6)-isothiocyanate (FITC) and 3-aminopropyltriethoxysilane (APTS)/SiO2 particles. The SiO2@FITC-APTS@MIPs were characterized by Fourier transform infrared (FT-IR), UV-vis spectrophotometer (UV-vis), fluorescence spectrophotometer, thermogravimetric analysis (TGA), confocal laser scanning microscope (CLSM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The as-synthesized SiO2@FITC-APTS@MIPs with an imprinted polymer film (thickness was about 100 nm) was demonstrated to be spherically shaped and had good monodispersity, high fluorescence intensity, and good selective recognition. Using fluorescence quenching as the detection tool, the largest fluorescence quenching efficiency (F0/F - 1) of SiO2@FITC-APTS@MIPs is close to 2.5 when the concentration of the LC is 1.0 μM L(-1). In addition, a linear relationship (F0/F - 1= 0.0162C + 0.0272) could be obtained covering a wide concentration range of 0-60 nM L(-1) with a correlation coefficient of 0.9968 described by the Stern-Volmer equation. Moreover, the limit of detection (LOD) of the SiO2@FITC-APTS@MIPs was 9.17 nM L(-1). The experiment results of practical detection revealed that the SiO2@FITC-APTS@MIPs as an attractive recognition element was satisfactory for the determination of LC in Chinese spirits. Therefore, this study demonstrated the potential of SiO2@FITC-APTS@MIPs for the recognition and detection of LC in food.

Synthesis and characterization of molecularly imprinted polymer embedded composite cryogel discs: application for the selective extraction of cypermethrins from aqueous samples prior to GC-MS analysis

Molecularly imprinted particles embedded composite cryogel discs specific for α-cypermethrin and β-cypermethrin were prepared.