Attapulgite modified magnetic metal-organic frameworks for magnetic solid phase extraction and determinations of benzoylurea insecticides in tea infusions

Covalent organic framework-sodium alginate-Ca2+-polyacrylic acid composite beads for convenient dispersive solid-phase extraction of neonicotinoid insecticides in fruit and vegetables

Neonicotinoids, the fastest-growing class of insecticides, have posed a multi-media residue problem with adverse effects on environment, biodiversity and human health. Herein, covalent organic framework-sodium alginate-Ca2+-polyacrylic acid composite beads (CACPs), facilely prepared at room temperature, were used in convenient dispersive solid-phase extraction (dSPE) and combined with high-performance liquid chromatography (HPLC) for the detection of five neonicotinoid insecticides (thiamethoxam, acetamiprid, dinotefuran, clothianidin, imidacloprid). CACPs can be completely separated within 1 min without centrifugation. After seven adsorption/desorption cycles, it maintained high extraction efficiencies (>90%). The developed method exhibited a wide linear range (0.01 ∼ 10 μg mL-1), low limits of detection (LODs, 0.0028 ∼ 0.0031 mg kg-1), and good repeatability (RSD ≤ 8.11%, n = 3). Moreover, it was applied to the determination of five neonicotinoids in fruit and vegetables (peach, pear, lettuce, cucumber, tomato), and recoveries ranged from 73.6% to 116.2%.

Synthesis of Magnetic Attapulgite Nanoparticles Via a Novel Surface Covalent Reaction Method and its Application in the Magnetic Solid Phase Extraction

In this study, the attapulgite nanoparticle was immobilized on the surface of magnetic nanoparticle Fe3O4 via a novel surface covalent reaction method for the magnetic solid phase extraction (MSPE) for the first time. The surface covalent reaction method has the advantages of controllable steps, and can make the magnetic attapulgite nanoparticle (MANP) have good homogeneity and high stability. Field emission scanning electron microscopy, equipped with an energy dispersive spectrometer, Nitrogen adsorption BET, X-ray diffraction and Fourier transform infrared spectroscopy were applied to characterize the prepared MANP, confirming that the attapulgite nanoparticle could be effectively immobilized on the surface of magnetic nanoparticle Fe3O4 via covalent reactions. Under optimal conditions of the MSPE experiment based on the MANP, the limits of detection were found to be 10 ng/mL for melamine and 3 ng/mL for cyromazine with a relative standard deviation < 10% by a high-performance liquid chromatography system. Meanwhile, 0.1 mg/mL melamine in milk and 0.1 mg/mL cyromazine in cucumber can also be detected according to our MSPE procedure. More importantly, the MANP still has good magnetism and enrichment efficiency after several decades of use. These results showed that the MANP prepared by our method is a kind of promising material for the MSPE.

Room-temperature fabrication of fluorinated covalent organic polymer @ Attapulgite composite for in-syringe membrane solid-phase extraction and analysis of domoic acid in aquatic products

A novel fluorinated covalent organic polymer @ attapulgite composite (F-COP@ATP) was prepared at room temperature for in-syringe membrane solid-phase extraction (SM-SPE) of domoic acid (DA) in aquatic products. Natural ore ATP has the advantages of low cost, good mechanical strength and abundant hydroxyl group on its surface, and in-situ modified F-COP layer can provide abundant adsorption sites. F-COP@ATP combining the advantages of F-COP and ATP, becomes an ideal adsorbent for DA extracting. Moreover, a high-throughput sample preparation strategy was carried out by using the F-COP@ATP membrane as syringe filter and assembling syringes with a ten-channel injection pump. In addition, the experimental factors were optimized, such as pH of extract, amount of adsorbent, velocity of extraction and desorption, type and volume of desorption solvent. The DA analytical method was established by SM-SPE-HPLC/tandem mass spectrometry. The method had a wide linear range with low limit of detection (0.344 ng/kg) and low limit of quantification (1.14 ng/kg). F-COP@ATP membrane can be reused more than five times. The method realized the analysis of DA in scallop and razor clam samples, which shows its application prospect in practical analysis. This study provided an efficient, low-energy and mild idea for preparing other reusable natural mineral ATP-based composite materials for separation and enrichment, which reduces the experimental cost and is closer to environmental protection and green chemistry to a certain extent.

The mechanism of intrinsic peroxidase (POD)-like activity of attapulgite

Natural attapulgite (ATP) is a promising substitute for existing artificial nanozymes due to its intrinsic enzymatic activity. However, the active center of ATP's inherent enzymatic activity has not yet been revealed, which limits its further design and activity optimization. Studying the active center of mineral materials can be extremely challenging due to their complexity. Here, we demonstrated that Fe is the primary element in ATP responsible for peroxidase (POD)-like activity through theoretical speculation and experimental verification. More importantly, we found that the ratio of Fe2+/Fe3+ is responsible for the district POD-like activity of ATP from different regions with the same Fe content. Additionally, three facile strategies, including grinding, heat treatment, and acid treatment, were demonstrated to increase the relative Fe content and thus optimize the POD-like activity of ATP. Finally, ATP was used to detect the concentration of H2O2, enabling the detection of low concentrations (0.11-1.76 mM) of H2O2. This study serves as a novel reference for the future design and performance optimization of nanozymes that are based on ATP and clay minerals.

Preparation of surface molecularly imprinted polymers with Fe3O4/ZIF-8 as carrier for detection of Dimethoate in cabbage

In this study, molecularly imprinted polymers (MIPs) were prepared for the specific recognition of organophosphorus pesticides and a rapid, efficient and simple method was established for the detection of dimethoate (DIT) in food samples. Fe3O4 magnetic nanoparticles were synthesized by co-precipitation, and Fe3O4/ZIF-8 complexes were prepared by a modified in-situ polymerization method, and then magnetic molecularly imprinted polymers (MMIPs) were prepared and synthetic route was optimized by applying density functional theory (DFT). The morphological characterization showed that the MMIPs were coarse porous spheres with an average particle size of 50 nm. The synthesized materials are highly selective for the organophosphorus pesticide dimethoate with an adsorption capacity of 461.50 mg·g-1 and are effective resistance to matrix effects. A novel method for the determination of DIT in cabbage was developed using the prepared MMIPs in combination with HPLC. The practical results showed that the method can meet the requirements for the determination of DIT in cabbage with recoveries of 85.6-121.1 % and detection limits of 0.033 μg·kg-1.

Well-defined Fe3O4@MIL-100(Fe) hollow nanoflower heterostructures for selective dection and monitoring of benzoylurea insecticides from food and water

Developing a platform for the selective detection and effective monitor of toxic contaminants is a major challenge to address organic contaminants contamination in environmental science. Here, for the first time, the thickness-controllable Fe3O4@MIL-100(Fe) heterogeneous materials with special hollow nanoflower (HFs) morphology had been synthesized. The morphology and shell thickness of the nano-petal could be tuned by changing the reaction time. The resultant Fe3O4@MIL-100(Fe) HFs exhibited the hollow nanoflower shapes and exposed abundant accessible active sites. The enrichment performance of Fe3O4@MIL-100(Fe) HFs was approximately 1.4-1.7 times that of spherical Fe3O4@MIL-100(Fe) composite for benzoylurea insecticides (BUs). Furthermore, the optimal sample achieved the wide linearity (0.05-500 ng mL-1) and low limits of detection, (0.003-0.01 ng mL-1) for BUs. The research provides a new strategy for highly sensitive detection and monitoring of harmful pollutant levels in the environment.

Bacteria-templated ZIF-8 embedded in polyacrylonitrile nanofibers as a novel sorbent for thin film microextraction of benzoylurea insecticides

In the present work, the rod-like ZIF-8 (ZIF8@E coli) was prepared by fast, easy and environmentally friendly method of biomimetic mineralization with Escherichia coli bacteria as a bio-template and was exploited for the first time in the microextraction. In this regard, electrospun nanofiber mats of polyacrylonitrile (PAN) and ZIF8@E coli were prepared by electrospinning method and used as a new sorbent for thin film microextraction (TFME) of benzoylurea insecticides such as Hexaflumuron and Teflubenzuron as model analytes. The PAN/ZIF8@E coli nanocomposite was characterized using electron scanning microscopy and various spectroscopy techniques. Factors affecting the proposed extraction method were screened and optimized using the experiment design strategy. Then, the model analytes were measured by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detector after microextraction. Satisfactory figures of merit were obtained for suggested TFME-HPLC-UV under optimum conditions. The suitable linearity varied in the range of 0.5-200 μg L-1 with R2 greater than 0.9968. The limit of detections for Hexaflumuron and Teflubenzuron were 0.12 and 0.15 μg L-1, respectively. The application of the method in the real sample was investigated by analyzing the selected analytes in environmental water and food samples. The spiking recovery of the selected analytes varied in the range of 93.0-109.8 % (RSD≤7.68). The results confirm the efficient application of this new sorbent in TFME approach. Considering the high availability, ease of production, and environmental friendliness of bacteria along with the significant improvement of metal-organic framework (MOF) growth efficiency, biomimetic mineralization is expected to be efficient method for the synthesis of ordered MOFs for use in extraction fields.

In situ growth of ZIF-67 to construct core-shell mosaic structural composites for efficient extraction of benzoylurea insecticides

A novel mosaic structure Silica@C/Co@ZIF-67 composite was synthesized by successfully embedding Co nanoparticles on the surface of silica spheres with the help of thermoplastic polyethyleneimine by carbon-reduction. The ZIF-67 half-shell layer structure was synthesized by the in-situ growth of ZIF-67 on the surface of silica spheres through the coordination of 2-methylimidazole with Co metal nodes. The composite was used as a magnetic solid-phase extraction adsorbent combined with high performance liquid chromatography-ultraviolet detector (HPLC-UV) for the extraction and determination of benzoylurea insecticides (BUs) in vegetables and tea. Based on the presence of π-π, hydrophobic and hydrogen bonding interactions between Silica@C/Co@ZIF-67 and BUs, the BUs were rapidly captured by the composites resulting in high adsorption performance. Under the optimal extraction parameters, the linear ranges were 0.3-200 µg L-1 for diflubenzuron, 0.6-200 µg L-1 for chlorbenzuron, and 1.0-200 µg L-1 for triflumuron, teflubenzuron, and flufenoxuron, with correlation coefficients (R2) greater than 0.9991. The limits of detection (LODs) of the method were 0.1-0.3 μg L-1, and the relative standard deviations (RSDs) were 1.2-3.0% for intra-day and 2.6-4.6% for inter-day. In the spiked recovery experiments of vegetables and tea, the recoveries of the five kinds of BUs ranged from 75.8 to 112.9%. In addition, after 10 repetitions using Silica@C/Co@ZIF-67, the recoveries of the five kinds of BUs were still as high as 78.4 to 83.9%.

Ionic liquid-modified UiO-66-NH2 as sorbent of dispersive solid-phase extraction for rapid adsorption and enrichment of benzoylurea insecticides

Ionic liquid (IL)-modified UiO-66-NH2 composite was prepared and used as sorbent of dispersed solid-phase extraction (dSPE) for extracting trace benzoylurea insecticides (BUs) from complex environmental matrices. The IL in framework endowed the prepared material had electropositive characteristics, which can produce interaction with electron rich guest molecules, such as BUs. The high thermal and chemical stability of UiO-66-NH2/IL enabled it to be reused for 16 times without significant reduction in adsorption performance. Due to the multiple forces including π-π, hydrogen bonding, and fluorine-fluorine interaction, UiO-66-NH2/IL showed good adsorption performance, short adsorption time (20 s) and rapid desorption ability (60 s) for BUs. Under the optimal conditions, the method exhibited wide linear range (0.02-500 ng mL-1) with correlation coefficient (R2) not worse than 0.9928, high enrichment factor (252-300), and low detection limit (0.005-0.4 ng mL-1). The dispersed solid phase extraction coupling with high-performance liquid chromatography-diode array detector (dSPE-HPLC-DAD) was successfully used to detection of BUs in real environmental samples and satisfactory recoveries were obtained (80.5%±2.4-118%±3.2). The results indicated that UiO-66-NH2/IL composite can be a potential sorbent for the preconcentration of trace insecticides in environmental samples.

Folic acid conjugated palygorskite/Au hybrid microgels: Temperature, pH and light triple-responsive and its application in drug delivery

Herein, folic acid conjugated poly (NIPAM-co-functional palygorskite-Au-co-acrylic acid) (FA-PNFA) hybrid microgels were fabricated by emulsion polymerization. The introduction of acrylic acid can increase the low critical solution temperature (LCST) of FA-PNFA from 36 °C at pH 5.5-42 °C at pH 7.4. Doxorubicin hydrochloride (DOX) was chosen as the load drug, the results show that the DOX release behavior is driven by temperature, pH and light. Cumulative drug release rate can reach 74 % at 37 °C and pH 5.5 while only 20 % at 37 °C and pH 7.4, which effectively avoided the early leakage of the drug. In addition, by exposing FA-PNFA hybrid microgels to laser irradiation, the cumulative release rate was increased by 5 % compared to the release rate under dark conditions. Functional palygorskite-Au as physical crosslinkers not only improves the drug loading content of microgels but also promotes the release of DOX through light drive. Methyl thiazolyl tetrazolium bromide (MTT) assay demonstrated that the FA-PNFA are nontoxic up to 200 μg mL-1 towards 4T1 breast cancer cell. Meanwhile, DOX-loaded FA-PNFA show more significant cytotoxicity than the free DOX. Confocal laser scanning microscope (CLSM) revealed that the DOX-loaded FA-PNFA could be efficiently taken by 4T1 breast cancer cells. FA-PNFA hybrid microgels not only improve the LCST of PNIPAM, but also endow the microgels with photostimulation responsiveness, which can release drugs in response to the triple stimulation response of temperature, pH and light, thus effectively reducing the activity of cancer cells, making them more promising for wider medical applications.

A robust and ultra-high-surface hydrogen-bonded organic framework promoting high-efficiency solid phase microextraction of multiple persistent organic pollutants from beverage and tea

Persistent organic pollutants (POPs) are widely distributed in the environment and are toxic, even at low concentrations. In this study, we first used hydrogen-bonded organic framework (HOF) to enrich POPs, based on solid phase microextraction (SPME). The HOF called PFC-1 (self-assembled by 1,3,6,8-tetra(4-carboxylphenyl)pyrene) has an ultra-high specific surface area, excellent thermochemical stability, and abundant functional groups, making it potential to be an excellent coating in SPME. And the as-prepared PFC-1 fiber have demonstrated outstanding enrichment abilities for nitroaromatic compounds (NACs) and POPs. Furthermore, the PFC-1 fiber was coupled with gas chromatography-mass spectrometry (GC-MS) to develop an ultrasensitive and practical analytical method with wide linearity (0.2-200 ng·L^-1), low detection limits for organochlorine pesticides (OCPs) (0.070-0.082 ng·L^-1) and polychlorinated biphenyls (PCBs) (0.030-0.084 ng·L^-1), good repeatability (6.7-9.9%), and satisfactory reproducibility (4.1-8.2%). Trace concentrations of OCPs and PCBs in drinking water, tea beverage, and tea were also determined precisely with the proposed analytical method.

Construction of hierarchically porous metal-organic framework HP-UiO-66-30% for sensitive determination of benzoylurea insecticides

Due to widespread application of benzoylurea insecticides (BUs) and its persistence in environment, the effective capture of benzoylurea insecticides residues in environment is an important issue of environmental safety monitoring. To obtain excellent adsorption performance, creating defective structure in metal-organic frameworks (MOFs) can be employed as the method for adjusting its properties. Zirconium(Ⅳ)-based MOF termed as UiO-66-30% was constructed with 2-aminoterephthalic acid (NH₂-BDC) and terephthalic acid (H₂BDC) as building blocks. After calcination and removal of thermal-sensitive ligand (NH₂-BDC), hierarchically porous UiO-66-30% (HP-UiO-66-30%) with multistage pore structure and good stability was obtained. The unique structure of HP-UiO-66-30% endowed it to achieve instantaneous equilibrium (within 2 min) when it was used as a dispersed solid phase extraction (d-SPE) adsorbent to extract BUs from environmental samples, greatly reducing the operation time. A wide linear range (0.05-200 ng mL^-1), good linearity (R² ≥ 0.9980), low detection limits (0.01-0.03 ng mL^-1) and quantification limits (0.05-0.1 ng mL^-1) were obtained for BUs. In addition, the HP-UiO-66-30% material possessed the good reusability and the adsorption capacity did not change significantly over 16 adsorption-desorption cycles. Finally, the established dispersed solid phase extraction-high performance liquid chromatography-diode array detector (d-SPE-HPLC-DAD) method was successfully applied to determination of BUs residues in environmental soil samples. The results demonstrated that HP-UiO-66-30% was an excellent sorbent for extraction BUs from environmental samples.

Facile synthesis of magnetic hypercrosslinked polymer for the magnetic solid-phase extraction of benzoylurea insecticides from honey and apple juice samples

In this work, a novel knitting aromatic polymer (KAP) was fabricated for the first time by knitting ferrocene with 1,3,5-tris(bromomethyl)-2,4,6-trimethylbenzene via Friedel-Crafts reaction, and then the KAP was magnetically functionalized with Fe₃O₄ nanoparticles to produce a magnetic KAP (M-KAP). Combining M-KAP based magnetic solid-phase extraction with high performance liquid chromatography-ultraviolet detection, a simple and sensitive method was developed for simultaneous determination of six benzoylurea insecticides (BUs) in honey and apple juice samples. In the optimized conditions, a good linearity for the BUs existed in the range of 1.67-1000 ng g^-1 for honey sample and 0.500-100.0 ng mL^-1 for apple juice sample. The limits of detection were 0.500-1.50 ng g^-1 and 0.150-0.400 ng mL^-1 for honey and apple juice sample, respectively. Satisfactory recoveries were in the range of 85.5-105.5% with RSDs ≤ 8.3%. The developed method demonstrated an excellent practicability for sensitive analysis of the BUs.

Fluorine-Functionalized Covalent-Organic-Framework-Coated Stir Bar for the Extraction of Benzoylurea Insecticides in Pear Juice and Beverage Followed by High-Performance Liquid Chromatography-Ultraviolet Detection

A fluorinated covalent organic framework (COF), named F-COF, was fabricated via simple room-temperature synthesis. With the characteristics of rich fluorine atoms, hydrophobicity, and large conjugated structure, F-COF was evaluated for the extraction of five benzoylurea insecticides (BUs) containing fluorine atoms, benzene ring, and urea bridge. Specifically, F-COF-coated stir bars were prepared by physical adhesion and exhibited higher extraction recovery (73-93 versus 40-85%) toward BUs than commercial stir bars in a shorter extraction time (50 min versus 24 h). The adsorption behavior of BUs on F-COF was explored, and it was assumed that the halogen bond (O-F), hydrophobic interaction, electrostatic interaction, and π-π stacking contributed to the adsorption. On the basis of it, a method combining stir bar sorptive extraction with liquid chromatography-ultraviolet detector was developed for trace analysis of five BUs. Under the optimal conditions, the limits of detection for BUs were found to be 0.301-0.672 μg/L, with the linear range of 1.0/2.0-500 μg/L and relative standard deviations of <8.0% (c = 5 μg/L and n = 7). The accuracy of the proposed method was validated by the recovery test, and the recoveries of target BUs in spiked pear juice and pear beverage were 82.0-113 and 84.0-112%, respectively.

TiO2@MOF-919(Fe-Cu) as a sorbent for the extraction of benzoylurea pesticides from irrigation water and fruit juices

The TiO₂@MOF-919(Fe-Cu) solid-phase extraction material was prepared by growing MOF-919(Fe-Cu) in situ on three-dimensional radial TiO₂ microspheres by a simple solvothermal method. This combination drew on both the resources of good single dispersion and extraction rate, which made it a better extraction material. It was accompanied with high-performance liquid chromatography (SPE-HPLC) for the separation and determination of four benzoylurea pesticides (triflumuron, chlorbenzuron, teflubenzuron and diflubenzuron) in afforestation irrigation water and juice samples (grape, peach and apple juices). Under the optimal conditions, the linearity of the method ranged from 1 to 400 μg L^-1 with a correlation coefficient (R²) ≥ 0.9994, while the detection limit was in the range of 0.40-0.56 μg L^-1 for the four pesticides. The adopted material showed good reusability and can be used no less than 10 times. The intra-day and inter-day precision were in the range of 1.78-3.24% and 4.06-5.08%, respectively. The proposed method was then successfully applied for the detection of benzoylurea pesticides in the spiked samples with good recoveries (72.3-108.4%) and good precision (5.15%) due to π-π and hydrophobic interactions between the analytes and adsorbent. The results show that the composite had the potential to be used as a SPE adsorbent for the enrichment and extraction of benzene ring structures containing imide groups in actual samples.

Monodispersed CaCO3@hydroxyapatite/magnetite microspheres for efficient and selective extraction of benzoylurea insecticides in tea beverages samples

A novel monodispersed CaCO₃@hydroxyapatite/magnetite microsphere (CaCO₃ @HAP/Fe₃O₄) was prepared via an in-situ growth strategy, and applied as an adsorbent for efficient and selective adsorption of benzoylurea insecticides (BUs) in various tea beverages samples. The sorbent exhibited uniformity in particle size, good mono-dispersibility and excellent solvent stability. The adsorption equilibrium of BUs (100 ng/mL) in 10 mL of tea beverages samples was achieved on 20 mg of CaCO₃ @HAP/Fe₃O₄ within 10 min. The adsorption followed pseudo-second-order kinetics and Langmuir models and the maximum adsorption capacities of 131.9-161.3 mg/g were accomplished via hydrophobic interactions, hydrogen bonding, and the affinity of F atom and Ca²⁺. Coupled with high performance liquid chromatography, the method offered wide linear ranges of 0.8-1000 ng/mL with correlation coefficients (r) ≥ 0.9995, low limits of detection of 0.2-0.3 ng/mL and large enrichment factors of 75.7-102. The recoveries ranged from 75.7%- 102% with intra- and inter-day precisions of 1.9%- 9.3% and 1.6%- 11.8%, respectively. In addition, CaCO₃ @HAP/Fe₃O₄ could be easily regenerated and reused at least 10 times with no significant loss of recovery. These results revealed an alternative strategy for fast and convenient determination of BUs in tea beverages samples and proved the great feasibility of CaCO₃ @HAP/Fe₃O₄ in the application for the selective adsorption of BUs.

Rapid determination of 2,4-diaminopyrimidine residues through sample pretreatment using immunomagnetic bead purification along with HPLC-UV

To reduce matrix interference and realize simultaneous detection of multiple homologous compounds (trimethoprim (TMP), diaveridine (DVD), ormetoprim (OMP), baquiloprim (BQP), and aditoprim (ADP) in pig, cattle, chicken, and fish muscles), an immunomagnetic bead (IMB)-based sample purification pretreatment with HPLC-UV was developed. A broad-spectrum monoclonal antibody (mAb, named 14C6) was prepared and conjugated with carboxylic-acid-functionalized magnetic nanoparticles using the active ester method to obtain IMBs for sample purification. The extraction solvent was optimized based on the extraction efficiency. Good linearity was observed for all the five analytes (10-200 μg/kg) with the LOD and LOQ of 5 and 10 μg/kg, respectively. The mean recoveries ranged from 62.5% to 76.9%, while the coefficient of variation was <12.2%. The IMB method afforded greater sample purification and enrichment than those achieved with the SPE column-based conventional method. Hence, the IMB-based sample purification is a useful tool to determine 2,4-diaminopyrimidine residues in edible animal tissues.

Metal-Organic Frameworks in Agriculture

Agrochemicals, which are crucial to meet the world food qualitative and quantitative demand, are compounds used to kill pests (insects, fungi, rodents, or unwanted plants). Regrettably, there are some important issues associated with their widespread and extensive use (e.g., contamination, bioaccumulation, and development of pest resistance); thus, a reduced and more controlled use of agrochemicals and thorough detection in food, water, soil, and fields are necessary. In this regard, the development of new functional materials for the efficient application, detection, and removal of agrochemicals is a priority. Metal-organic frameworks (MOFs) with exceptional sorptive, recognition capabilities, and catalytical properties have very recently shown their potential in agriculture. This Review emphasizes the recent advances in the use of MOFs in agriculture through three main views: environmental remediation, controlled agrochemical release, and detection of agrochemicals.

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.

Phenylboronic acid-functionalized cross-linked chitosan magnetic adsorbents for the magnetic solid-phase extraction of benzoylurea pesticides

In this study, a 4-formylphenylboronic acid-modified cross-linked chitosan magnetic nanoparticle (FPBA@CCHS@Fe₃ O₄ ) was fabricated. The synthesized material was utilized as the magnetic solid-phase extraction adsorbent for the enrichment of six benzoylurea pesticides. In addition to B-N coordination, FPBA@CCHS@Fe₃ O₄ interacts with benzoylureas through hydrogen bonds and π-π stacking interaction on account of rich active groups (amino and hydroxyl) and aromatic rings in structure. Compared to traditional extraction methods, less adsorbent (20 mg) and reduced extraction time (3 min) were achieved. The adsorbent also exhibited good reusability (no less than 10 times). Coupled with a high-performance liquid chromatography-diode array detector, satisfactory recoveries (89.1-103.9%) and an acceptable limit of detection (0.2-0.7 μg/L) were obtained. Under optimized conditions, the established method was successfully applied to the tea infusion samples from six major tea categories with acceptable recoveries ranging from 76.8 to 110%, indicating its application potential for the quantitative detection of pesticides in complex matrices.

Co-precipitation based on layered double hydroxides and anionic surfactants for preconcentration of six benzoylurea insecticides in soft drinks before simultaneous analysis by high-performance liquid chromatography

Layered-double hydroxides (LDHs) modified with anionic surfactants via a co-precipitation method were developed for preconcentrating and simultaneous analysis of six benzoylurea insecticides (BUs) by high-performance liquid chromatography (HPLC). The anionic surfactants with different chain lengths, including sodium dodecylbenzene sulfonate (SDBS), sodium dodecyl sulfate (SDS), sodium 1-nonane sulfonate (SNS), and sodium 1-hexane sulfonate monohydrate (SHS) were investigated to improve the extraction efficiency of LDHs. The SDBS-LDHs provided the highest efficiency for the enrichment of the BUs studied. Under the chosen conditions, enrichment factors in the range of 38-69 and detection limits in the range of 0.1-0.3 μg L^-1 were achieved. Good reproducibilities (RSD < 13.8%) and recoveries (71.4-118.7%) were also obtained. The proposed preconcentration method, used as an in situ procedure offers rapid and simple simultaneous preparation of LDHs and extraction of BUs. The method was successfully applied for residue analysis of BUs in fruit- and flower-derived soft drink samples.

Fabrication of a Magnetic Fluorinated Covalent Organic Framework for the Selective Capture of Benzoylurea Insecticide Residue in Beverages

Efficient capture of benzoylurea insecticide (BU) residue in food is a vital procedure for food safe monitoring. Herein, a core-shell structured magnetic fluorinated covalent organic framework with good magnetic responsiveness and abundant fluorine affinity sites was successfully synthesized, suitable for magnetic solid-phase extraction (MSPE) of BUs. Using a room-temperature synthesis strategy, the magnetic fluorinated covalent organic framework was fabricated by in situ polymerization of 1,3,5-tris(4-aminophenyl) triazine (TAPT) and 2,3,5,6-tetrafluoroterephthaldehyde (TFTA) on the surface of carboxylated Fe₃O₄ nanoparticles. The competitive adsorption experiment and molecular simulation verified that this magnetic fluorinated covalent organic framework possesses favorable adsorption affinity for BUs. This magnetic fluorinated covalent organic framework could be easily regenerated and reused at least eight times with no reduction of enrichment performance. Combining this magnetic fluorinated covalent organic framework-based MSPE with high-performance liquid chromatography-tandem mass spectrometry, a novel sensitive method for the analysis of BUs was developed. In yellow wine and fruit juice samples, good linear correlations were obtained for BUs in the range of 10-2000 and 20-4000 ng·L^-1, respectively. The limit of quantitation of the BUs ranged from 1.4 to 13.3 ng·L^-1 in the two beverage matrices. Desirable precision was achieved, with intraday and interday relative standard deviations lower than 11%.

Development of a SPE/GC-MS method for the determination of organophosphorus pesticides in food samples using syringe filters packed by GNP/MIL-101(Cr) nanocomposite

In this study, we report the synthesis and application of a nanocomposite comprising metal-organic framework MIL-101(Cr) and graphene nanopowder (GNP) as a promising sorbent for the extraction of organophosphorus pesticides (OPPs) in juices, water, vegetables and honey samples. A syringe filter, for the first time, was used to host the synthesized nanocomposite and extract the OPPs followed by GC-MS analysis. Different characterization methods including XRD, FTIR, TGA, BET and SEM were employed to confirm the formation of studied nanocomposite. The results indicated that the GNP/MIL-101(Cr) could provide higher capacity for adsorption of OPPs and lower detection limit compared to pristine MIL-101(Cr). The detection limits were 0.005 to 15.0 µg/Kg and the linear range found between 0.05 and 400 µg/Kg. The proposed method showed very good repeatability with the RSD values ranging from 2.9% to 7.1%. The recoveries were between 84% -110% with the spiked levels of 2.0-100.0 µg/Kg.

Application of electrospun polyacrylonitrile/Zn-MOF-74@GO nanocomposite as the sorbent for online micro solid-phase extraction of chlorobenzenes in water, soil, and food samples prior to liquid chromatography analysis

An online micro solid-phase extraction (online-µSPE) using electrospun nanofibers, as an efficient sorbent, was developed to extract chlorobenzenes (CBs) from paddy soil, agricultural wastewater, and food samples (fruit juices, vegetables, rice samples) followed by high performance liquid chromatography analysis. Electrospun nanofibers were fabricated using a nanocomposite containing polyacrylonitrile and Zn-metal organic framework 74 @graphene oxide (PAN/Zn-MOF-74@GO), and subsequently characterized. Under the optimal conditions, acceptable linearity was obtained in the range of 0.25-700.00 ng mL^-1 for 1,2-dichlorobenzene (1,2-DCB) and 2.50-700.00 ng mL^-1 for both 1,2,3-trichlorobenzene (1,2,3-TCB) and 1,2,4-trichlorobenzene (1,2,4-TCB) with determination coefficients ≥ 0.9991. The limits of detection ranged from 0.08 to 1.10 ng mL^-1. The intra-day and inter-day single fiber and fiber to fiber relative standard deviations were observed in the range of 4.1%-9.5% and 5.8%-12.1%, respectively. The performance of this method was examined by determining the target analytes in the different spiked samples.

A novel dispersive magnetic solid phase microextraction using ionic liquid-coated amino silanized magnetic graphene oxide nanocomposite for high efficient separation/preconcentration of toxic ions from shellfish samples

A novel dispersive magnetic solid phase microextraction (d-MSPE) method using ionic liquid-coated amino silanized magnetic graphene oxide (MGO@SiO₂-APTES-IL) as adsorbent has been established for enriching and extracting lead(II), copper(II) and cadmium(II) in shellfish samples. The novel nanocomposite was proved synthesized successfully by various characterization technologies. Parameters that could affect the recoveries of target ions were investigated and optimized focusing on adsorption and desorption using Box-Behnken design of response surface methodology (BBD-RSM). The limits of detection (LODs) for three target heavy metal ions were 2.42, 3.36, 3.75 ng L^-1, respectively. Additionally, the maximum adsorption capacities of the nanocomposite for target ions were 251.23, 138.51, 159.31 mg g^-1 at 298 K, respectively, the nanoadsorbent can be regenerated without significant adsorption capacities loss for four times. These observations revealed that the novel nanocomposite can be used as an excellent adsorbent for separation and preconcentration of the target ions.

New frontiers and prospects of metal-organic frameworks for removal, determination, and sensing of pesticides

Pesticides have been widely used in agriculture to control, reduce, and kill insects. Humans are also being using pesticides to control insidious animals in daily life. By these practices, a huge volume of pesticides is introduced to the environment. Despite broad-spectrum applicability, pesticides also have hazardous effects on both humans and animals at high and low concentrations. Long-term exposure to pesticides can cause different diseases, like leukemia, lymphoma, and cancers of the brain, breasts, prostate, testis, and ovaries. Reproductive disorders from pesticides include birth defects, stillbirth, spontaneous abortion, sterility, and infertility. Therefore, the application of determination and treatment methods for pre-concentration and removal of these toxic materials from the environment appears a vital concern. To date, different materials and approaches have been employed for these purposes. Among these approaches, multifunctional metal-organic frameworks (MOFs)-assisted adsorption and determination processes have always been in the spotlight. These facts are due to exclusive properties of MOFs in terms of the crystallinity, large surface area, high chemical, and physical stability, and controllable structure as well as unique features of adsorption and determination process in terms of simple, easy, cheap, available method and ability to use in large and industrial scales. In the present work, we illustrate the exceptional features of MOFs as well as the possible mechanism for the adsorption of pesticides by MOFs. The use of these fantastic materials for pre-concentration and removal of pesticides are extensively explored. In addition, the performance of MOFs was compared with other adsorbents. Finally, the new frontiers and prospects of MOFs for the determination, sensing, and removal of pesticides are presented.

Phosphonium-based deep eutectic solvent coupled with vortex-assisted liquid-liquid microextraction for the determination of benzoylurea insecticides in olive oil

In this study, a novel method using a phosphonium-based deep eutectic solvent coupled with vortex-assisted liquid-liquid microextraction was investigated for the enrichment and separation of five benzoylurea insecticides in olive oil. The experimental factors affecting the extraction efficiency, including the extractant type, deep eutectic solvent volume, extraction time, and extraction mode, were optimized. Under optimal conditions, good linearity was observed for all target analytes, with correlation coefficients (r) ranging from 0.9971 to 0.9998; the limits of detection were in the range of 1.5 to 7.5 μg/L, and the recoveries of analytes using the proposed method ranged between 66.9 and 111.0%. The simple, rapid, and effective method was successfully applied for detecting target analytes in olive oil sample.

Magnetic boron nitride nanosheets as a novel magnetic solid-phase extraction adsorbent for the determination of plant growth regulators in tomatoes

A novel magnetic boron nitride nanosheets (Fe₃O₄@BNNSs) composite-based magnetic solid-phase extraction (MSPE) method was employed to analyse six plant growth regulators (PGRs) in tomatoes combined with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The novel Fe₃O₄@BNNSs composite was prepared via an in situ chemical coprecipitation process and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). Several factors that may affect the extraction efficiencies were optimized. Under the optimal factors, low limits of detection (0.002-0.010 ng g^-1), good linear ranges (0.05-10 ng g^-1) and satisfactory precisions (intra-day: 1.2%-3.9%; inter-day: 2.1%-6.9%) were achieved. The established approach was successfully employed to extract and determine PGRs in tomatoes, and the spiked recoveries were between 85.2 and 109.0%.

DETA impregnated attapulgite hybrid ZIF-8 composite as an adsorbent for the adsorption of aspirin and ibuprofen in aqueous solution

The diethylenetriamine (DETA) impregnated modified attapulgite hybrid ZIF-8 composite is a new type of amine impregnated hybrid MOF adsorbent, which has an excellent ability to remove aspirin and ibuprofen from aqueous solution.

Cyanuric chloride-imidazole dendrimer functionalized nanoparticles as an adsorbent for magnetic solid phase extraction of quaternary ammonium compounds from fruit and vegetable puree based infant foods

A novel magnetic solid-phase extraction (MSPE) material (Fe₃O₄@SiO₂-NH₂-G2) had been prepared and employed for adsorption and analysis of seven quaternary ammonium compounds (QACs) in infant fruit and vegetable products coupled with high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). In this paper, Fe₃O₄@SiO₂-NH₂-G2 was synthesized based on Fe₃O₄@SiO₂-NH₂ and dendrimer (G2) consisting of cyanuric chloride and imidazole. The morphology, configuration and magnetic behavior of the magnetic material were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Critical parameters affecting extraction efficiency, such as the adsorbent amount, sample pH, extraction time, the type of eluent, and desorption time, were optimized. The proposed method provided good linearity with the correlation coefficients (R²) of 0.9992-0.9999, low limits of detection (LODs) (0.05-0.50 μg kg^-1) and limits of quantitation (LOQs) (0.20-2.00 μg kg^-1). The satisfactory method recoveries in three spiked infant fruit and vegetable products samples were between 80.12% and 101.35% with the relative standard deviations (RSDs) less than 12.04%. In summary, the established method was an effective sample preparation method and showed good prospect for the analysis of QACs in complex matrices.

Metal-organic framework for the extraction and detection of pesticides from food commodities

Pesticide residues in food matrices, threatening the survival and development of humanity, is one of the critical challenges worldwide. Metal-organic frameworks (MOFs) possess excellent properties, which include excellent adsorption capacity, tailorable shape and size, hierarchical structure, numerous surface-active sites, high specific surface areas, high chemical stabilities, and ease of modification and functionalization. These promising properties render MOFs as advantageous porous materials for the extraction and detection of pesticides in food samples. This review is based on a brief introduction of MOFs and highlights recent advances in pesticide extraction and detection through MOFs. Furthermore, the challenges and prospects in this field are also described.

Recent Applications of Magnetic Nanoparticles in Food Analysis

Nanotechnology has become a topic of interest due to the outstanding advantages that the use of nanomaterials offers in many fields. Among them, magnetic nanoparticles (m-NPs) have been one of the most widely applied in recent years. In addition to the unique features of nanomaterials in general, which exclusively appear at nanoscale, these present magnetic or paramagnetic properties that result of great interest in many applications. In particular, in the area of food analysis, the use of these nanomaterials has undergone a considerable increase since they can be easily separated from the matrix in sorbent-based extractions, providing a considerable simplification of the procedures. This allows reducing cost and giving fast responses, which is essential in the food trade to guarantee consumer safety. These materials can also be easily tunable, providing higher selectivity. Moreover, their particular electrical, thermal and optical characteristics allow enhancing sensor signals, increasing the sensitivity of the approaches based on this type of device. The aim of this review article is to summarise the most remarkable applications of m-NPs in food analysis in the last five years (2016–2020) showing a general view of the use of such materials in the field.

Digital image colorimetry detection of carbaryl in food samples based on liquid phase microextraction coupled with a microfluidic thread-based analytical device

This research used a digital image colorimetry (DIC) method to detect carbaryl in food samples using effervescence-assisted liquid phase microextraction based on solidification of switchable hydrophilicity solvent combined with a microfluidic thread-based analytical device (EA-LPME-SSHS-μTAD). 1-naphthol, the hydrolysate of carbaryl, was extracted into octanoic acid by the adjustment of pH values of the sample solution and separated through solidification in an ice bath. Then 1-naphthol contained in the extracted solution was coupled with 4-methoxybenzenediazonlum tetrafluoroborate (MBDF) fixed on the μTAD to produce tangerine compounds. The inherent colour variation was captured by a smartphone and processed to calculate the intensity (I). Under the optimal conditions, the limit of quantification was within 0.020-0.027 mg kg^-1. The recovery was varied in the range from 92.3% to 105.9% with a relative standard deviation (RSD) below 5%. The developed method provides an alternative strategy to extract and detect pesticides for food samples.