Synthesis of a zinc-based metal-organic framework with histamine as an organic linker for the dispersive solid-phase extraction of organophosphorus pesticides in water and fruit juice samples

Synthesis of green nanosorbent from bovine serum albumin and curcumin for magnetic solid phase extraction of pesticides from food samples

For the first time, a magnetic carbon nanocomposite was synthesized using one-step hydrothermal procedure, employing bovine serum albumin, curcumin, and ferric ammonium citrate. Additionally, the application of this novel composite as an adsorbent for magnetic dispersive solid phase extraction of fungicides and pesticides from water and food samples is a unique aspect of this study. Under optimum conditions (salt concentration: 5.0% w/v, pH: 7.0, desorption solvent: ethanol, sorbent amount: 20 mg, extraction time: 20 min, desorption time: 3 min, stirring rate: 500 rpm, sample volume: 30 mL, extraction temperature: room temperature, and desorption solvent volume: 150 μL) linearity (2.5 to 1400 ng mL-1), coefficients of determination (R2 ≥ 0.997), limits of detection (0.75 to 1.5 ng mL-1), and limits of quantification (2.5 to 5.0 ng mL-1) were achieved. The method validation results showed extraction recovery ranging from 71.2% to 93.4%, and preconcentration factors ranging from 142.5 to 186.1.

Applications of metal organic frameworks in dispersive micro solid phase extraction (D-μ-SPE)

Metal-organic frameworks (MOFs) are a fascinating family of crystalline porous materials made up of metal clusters and organic linkers. In comparison with other porous materials, MOFs have unique characteristics including high surface area, homogeneous open cavities, and permanent high porosity with variable shapes and sizes. For these reasons, MOFs have recently been explored as sorbents in sample preparation by solid-phase extraction (SPE). However, SPE requires large amounts of sorbents and suffers from limited contact surfaces with analytes, which compromises extraction recovery and efficiency. Dispersive SPE (D-SPE) overcomes these limitations by dispersing the sorbents into the sample, which in turn increases contact with the analytes. Miniaturization of the microextraction procedure, particularly the amount of sorbent reduces the amount consumed of the organic solvent and shorten the time required to attain the equilibrium state. This may explain the reported high efficiency and applicability of MOFs in dispersive micro SPE (D-µ-SPE). This method retains all the advantages of solid phase extraction while also being simpler, faster, cheaper, and, in some cases, more effective in comparison with D-SPE. Besides, D-µ-SPE requires smaller amounts of the sorbents which reduces the overall cost, and the amount of waste generated from the analytical process. In this review, we discuss the applications of MOFs in D-µ-SPE of various analytes including pharmaceuticals, pesticides, organic dyes from miscellaneous matrices including water samples, biological samples and food samples.

A fast and simple procedure for the synthesis of a zinc and 1,4-benzene dicarboxylic acid metal-organic framework and its evaluation as a sorbent for dispersive micro solid phase extraction of pesticide residues

In this work, Zn-1,4-benzenedicarboxylate metal-organic framework was synthesized by a simple hydrothermal process and used in dispersive micro solid phase extraction of some pesticide from various fruit juice and water samples. Seven widely consumed pesticides in agriculture (chlorpyrifos, haloxyfop-R-methyl, oxadiazon, diniconazole, clodinafop-propargyl, fenpropathrin, and fenaxoprop-p-ethyl) were selected as target analytes. In this work, dispersive micro solid phase extraction was followed by a liquid phase microextraction method to achieve more enrichment of the analytes, and the enriched analytes were quantified using a gas chromatography-flame ionization detector. The sorbent was authenticated by Fourier transform infrared spectrophotometry, X-ray diffraction, energy dispersive X-ray analysis, and scanning electron microscope imaging. The factors affecting the extraction efficiency of the developed method were investigated, and the validation of the method under the optimized extraction conditions presented satisfactory results for precision and trueness, with limits of detection and quantification in the ranges of 0.50-0.90 and 1.5-2.7 μg L-1, respectively. Enrichment factors and extraction recoveries were in the ranges of 239-392% and 47-78%, respectively. One river water and some fruit and vegetable juice samples were analyzed by the recommended method, and the obtained recoveries were between 90% and 102%.

X-ray diffraction and its emerging applications in the food industry

X-ray diffraction (XRD) is an analytical technique that has found several applications focusing on the identification of crystal structure, space groups, plane, and orientation, in addition to qualitative and quantitative phase identification, and polymorphism behavior. An XRD diffractogram pattern/Bragg's peak can also provide valuable information that can be used for various food applications. While this review details the fundamental principles of XRD, the types of XRD systems, instrumentation, and the components thereof, the focus is to serve as a structured resource on explored applications of XRD in food, majorly revolving around food quality and safety. While recent studies relevant to the field are highlighted, leads for futuristic prospects are presented. With its unique approach, the XRD analysis can prove to be a rapid, robust, and sensitive nondestructive approach to food quality evaluation. Recent reports indicate its scope for nonconventional applications such as the assessment of 3D printability of foods, ice crystal formation, and screening food adulterants. Studies also highlight its scope to complement or replace conventional food quality testing approaches that involve the usage of chemicals, extensive sample preparation procedures, derivatization steps and demand long testing times.

Dispersive solid-phase extraction based on zirconium metal-organic framework coupled with gas chromatography-mass spectrometry for determining sugar phosphates in biological samples

BACKGROUND

Sugar phosphates (SPx) play important role in the metabolism of the organism. SPx such as glycerate 3-phosphate, fructose 6-phosphate and glucose 6-phosphate in biological samples have the poor stability, similar structure and low abundance, which make their separation and detection more challenging.

METHOD

UiO-66-NH2 and ZrO2 coated SiO2(SBA-15) hard-core-shell adsorbents (UiO-66-NH2@SBA-15 and ZrO2@SBA-15) were synthesized, which were further used for dispersive solid-phase extraction for enriching the SPx in biological samples. The protocol was developed by UiO-66-NH2@SBA-15 and ZrO2@SBA-15 coupled with gas chromatography-mass spectrometry for the detection of trace SPx. The univariate experiment and response surface methodology were used to optimize the adsorption and desorption conditions.

RESULTS

The adsorbents showed excellent adsorption capacity and specificity towards SPx, which were proved by adsorption and selective experiments. Under the optimized conditions, there were good linearity within the range of 5.0-5000.0 ng mL-1, low limits of detection (0.001-1.0 ng mL-1), low limits of quantification (0.005-5.0 ng mL-1) and good precision (relative standard deviation less than 14.7 % for intra-day and inter-day). The satisfactory recoveries (89.1-113.8 %) and precision (0.5-14.6 %) were obtained when the sorbents were used to extract SPx from serum, saliva and cell samples. Moreover, UiO-66-NH2@SBA-15 was applied to the quantitative analysis of SPx from gastric cancer patients, because of a higher adsorption capacity (169.5-196.1 mg g-1).

CONCLUSIONS

UiO-66-NH2@SBA-15 showed great potential in the extraction of SPx in biological samples, which was beneficial to find out the metabolic change of SPx and explain the pathogenesis of the disease.

Defective UiO-66/cellulose nanocomposite aerogel for the adsorption of heterocyclic aromatic amines

Heterocyclic aromatic amines (HAAs), arising as chemical derivatives during the high-temperature culinary treatment of proteinaceous comestibles, exhibit notable carcinogenic potential. In this paper, a composite aerogel (AGD-UiO-66) with high-capacity and fast adsorption of HAAs was made with anchoring defective UiO-66 (D-UiO-66) mediated by lauric acid on the backbone of cellulose nanofibers (CNF). AGD-UiO-66 with hierarchical porosity reduced the mass transfer efficiency for the adsorption of HAAs and achieved high adsorption amount (0.84-1.05 μmol/g) and fast adsorption (15 min). The isothermal adsorption model demonstrated that AGD-UiO-66 belonged to a multilayer adsorption mechanism for HAAs. Furthermore, AGD-UiO-66 was successfully used to adsorb 12 HAAs in different food (roasted beef, roasted pork, roasted salmon and marinade) with high recoveries of 94.65%-104.43%. The intrinsic potential of AGD-UiO-66 demonstrated that it could be widely applicable to the adsorption of HAAs in foods.

Synthesis of polyethylene glycol-grafted magnetic nanoparticles for the fast and efficient extraction of anabolic substances from human urine

Anabolic steroids and β-agonists are commonly prohibited substances found in doping control studies; therefore, the determination of anabolic substances in biological samples is crucial. To analyze the anabolic compounds in urine, an adsorbent, polyethylene glycol (PEG)-grafted magnetic nanoparticle material (Fe3O4@SiO2-PEG), with low toxicity and strong biocompatibility was prepared in this investigation. Compared to those of Fe3O4 and Fe3O4@SiO2, the grafted PEG chains (approximately 5.4 wt.%) on the magnetic nanoparticles improved the extraction efficiencies by factors of 3.9-17.0 and 2.5-2.9, respectively, likely due to the electrostatic attraction and hydrogen bonding. To achieve maximum extraction efficiency, several extraction parameters were optimized, including the kind and volume of desorption solvent, pH, and the extraction and desorption time. The standard curves were linear within the range of 0.5-20 μg/L for methyltestosterone and trenbolone, and 0.02-5 μg/L for clenbuterol. The limits of detection for the three drugs were 0.01-0.12 μg/L. The limits of quantification were 0.02-0.40 μg/L. The levels of precision of the optimized method were assessed based on the respective intra- and inter-day and batch-to-batch relative standard deviations in the ranges of 3.2-5.2 % (n = 5), 5.9-11.3 % (n = 4), and 6.7-9.2 % (n = 3). The Fe3O4@SiO2-PEG nanoparticles could exclude urine matrix interferences (matrix effect of 91.8-98.1 %) and achieve satisfactory recoveries (75.5-116.1 %), affording sensitive and accurate determination of trace anabolic substances in urine.

Eco-friendly thermosensitive magnetic-molecularly-imprinted polymer adsorbent in dispersive solid-phase microextraction for gas chromatographic determination of organophosphorus pesticides in fruit samples

A thermosensitive magnetic-molecularly-imprinted polymer (TMMIP) was successfully prepared in an aqueous medium. The TMMIP was applied as an effective adsorbent in dispersive solid-phase microextraction for the selective enrichment of five organophosphorus pesticides (OPPs; diazinon, fenitrothion, fenthion, parathion-ethyl, and ethion) before analysis by gas chromatography. The polymerization was performed using mixed-valence iron hydroxide nanoparticles as the magnetic support, N-isopropyl acrylamide as the thermosensitive monomer, ethion as the template, and methacrylic acid as the functional monomer. The adsorption and desorption mechanisms of OPPs depend on their interactions with the adsorbents and solution temperature. Our methodology provides good linearity (0.50-2000 µgL-1), with a correlation determination of R2 > 0.9980, low limit of detection (0.25-0.50 µgL-1), low limit of quantitation (0.50-1.50 μg L-1), and high precision (%RSD < 7%). The developed method demonstrates excellent applicability for accurately and efficiently determining OPP residuals in fruit and vegetable samples with good recoveries (93-117%).

Magnetic functionalized graphene oxide combined with ultra-high performance liquid chromatography for trace detection of succinate dehydrogenase inhibitor fungicides in food

In this study, an efficient, sensitive, and convenient magnetic solid-phase extraction method combined with ultra-high performance liquid chromatography-tandem mass spectrometry (MSPE-UHPLC-MS/MS) was developed for the simultaneous determination of 19 succinate dehydrogenase inhibitor fungicide residues in six different food matrices The synthesized tetraethylenepentamine magnetic graphene oxide nanocomposite showed the advantages of good dispersibility, large specific surface area (113.93 m2 /g) and large pore volume (0.25 cm3 /g), making it an ideal succinate dehydrogenase inhibitor pretreatment adsorbent. The MSPE-UHPLC-MS/MS method showed linearity in the range of 5.0-800.0 μg/kg, with a correlation coefficient (R2 ) > 0.99, and a limit of quantification of 5 μg/kg. The recovery of succinate dehydrogenase inhibitor fungicides was in the range of 71.2%-119.4%. The MSPE method is simple, rapid, and efficient, making it an ideal alternative to sample pretreatment in the determination of trace succinate dehydrogenase inhibitor fungicides in complex matrices.

Electrospun mesh pattern of polyvinyl alcohol/zirconium-based metal-organic framework nanocomposite as a sorbent for extraction of phthalate esters

Herein, an electrospun composite polyvinyl alcohol/zirconium-based metal-organic frameworks (PVA@UiO-66) nanofiber coating was prepared on the surface of stainless steel mesh (SSM) and then utilized as novel sorbent for the extraction of phthalate esters (PEs) in milk and water samples. Gas chromatography equipped with a flame ionization detector (GC-FID) was used for the quantitative determination of extracted analytes. The SSM coated with PVA@UiO-66 was used in a polypropylene syringe to fabricate the solid-phase extraction (SPE) device. The PVA@UiO-66 nanofiber coating was confirmed using X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy analysis (FT-IR), and field emission scanning electron microscopy (FESEM). The effective parameters of the extraction efficiency including volume and type of desorption solvent, sample volume, ionic strength, pH, extraction flow rate, and desorption flow rate were optimized. At the optimal extraction conditions, the calibration plots for phthalate esters were linear within the range of 0.05-100 ng mL-1 and, low detection limits (0.015-0.06 ng mL-1). Finally, this semi-automated SPE was used for the extraction and detection of phthalate esters (PEs) in milk and various environmental real water samples. The results showed good precision with acceptable and satisfactory extraction recovery values ranging from 89.5 to 99.2% and relative standard deviations (RSDs%) ranging from 4.5 to 6.9%.

Highly defective copper-based metal-organic frameworks for the efficient adsorption and detection of organophosphorus pesticides: An experimental and computational investigation

Organophosphorus pesticide (OP) residues pose a serious threat to human health, motivating the search for novel adsorbents and detection methods. Herein, defective copper-based metal organic frameworks (Cu-MOFs) were synthesized by the reaction of Cu²⁺ ions and 1,3,5-benzenetricarboxylate linkers in the presence of acetic acid. As the amount of acetic acid increased, the crystallization kinetics and morphology of the Cu-MOFs changed, leading to mesoporous Cu-MOFs with many large surface pores (defects). Adsorption studies of OPs revealed the defective Cu-MOFs showed faster pesticide adsorption kinetics and higher pesticide adsorption capacities. Density functional theory calculations showed that pesticide adsorption in the Cu-MOFs was mainly electrostatic. A dispersive solid phase extraction method was developed based on a defective Cu-MOF-6 for rapidly extracting pesticides from food samples. The method allowed pesticide detection over a wide linear concentration range, low limits of detection (0.0067-0.0164 µg L^-1) and good recoveries in pesticide-spiked samples (81.03-109.55%).

The elimination and extraction of organosulfur compounds from real water and soil samples using metal organic framework/graphene oxide as a novel and efficient nanocomposite

In the present work, an efficient metal organic framework/graphene oxide (MOF-801/GO) sorbent was fabricated and employed for the detection of organosulfur pesticides (OSPs) in real samples using gas chromatography-flame photometric detection (GC-FPD). The optimal extraction parameters for the suggested solid-phase extraction (SPE) include sorbent amount (60 mg), extraction solvent (acetonitrile) and extraction time (5 min). The linear dynamic ranges and detection limits for organosulfur pesticides (OSPs) samples under above extraction conditions were ranged from 0.5 to 300 μg L^-1 and 0.1-1.1 μg L^-1, respectively. Moreover, the proposed SPE/GC-FDP method was applied for the analysis of pesticides in different real environmental water and soil samples. The obtained recoveries of the analytes in were between 92.0 and 106.8% and relative standard deviation (RSD) values were lower than 9.2%. The application of the MOF-801/GO as a sorbent in dSPE of OSPs analytes showed to be reliable, fast and sensible methodology for pesticides monitoring in different environmental samples.

Review of extraction and detection techniques for the analysis of pesticide residues in fruits to evaluate food safety and make legislative decisions: Challenges and anticipations

Fruits are vital parts of the human diet because they include necessary nutrients that the body needs. Pesticide use has increased dramatically in recent years to combat fruit pests across the world. Pesticide usage during production, on the other hand, frequently results in undesirable residues in fruits after harvest. Consumers are concerned about pesticide residues since most of the fruits are directly consumed and even recommended for the patients as dietary supplements. As a result of this worry, pesticide residues in fruits are being randomly monitored to re-assess the food safety situation and make informed legislative decisions. To assess the degree of pesticide residues in fruits, a simple and quick analytical procedure is usually required. As a result, pesticide residue detection (using various analytical techniques: GC, LC and Biosensors) becomes critical, and regulatory directives are formed to regulate their amounts via the Maximum Residue Limit (MRL). Over the previous two decades, a variety of extraction techniques and analytical methodologies for xenobiotic's efficient extraction, identification, confirmation and quantification have been developed, ranging from traditional to advanced. The goal of this review is to give readers an overview of the evolution of numerous extraction and detection methods for pesticide residue analysis in fruits. The objective is to assist analysts in better understanding how the ever-changing regulatory landscape might drive the need for new analytical methodologies to be developed in order to comply with current standards and safeguard consumers.

Opioid Drug Detection in Hair Samples Using Polyoxometalate-Based Frameworks

A series of two-dimensional (2D) polyoxometalate-based frameworks, [Ln₃(PDA)₃(H₂O)₆(PMo₁₂O₄₀)]·xH₂O (Ln = La (1); Ce (2); Pr (3); Nd (4); PDA = 1,10-phenanthroline-2,9-dicarboxylate), have been synthesized and structurally characterized by various analytical techniques. Single-crystal X-ray diffraction reveals that 1-4 have a unique 2D layer structure in which Keggin anions have coordinated upward and downward the plane, and this feature makes them suitable candidates for surface binding of common drugs via supramolecular and electrostatic interactions. Also, the ability of 1-4 (as the first polyoxomolybdate-containing frameworks) as sorbents for the extraction and quantitative determination of opioid drugs (morphine, methadone, and pethidine) was investigated by using dispersive micro-solid-phase extraction (D-μSPE) and high-performance liquid chromatography (HPLC). The method showed wide linear ranges in the range of 0.3 to 300 ng mg^-1 and low limits of detection (LODs) ranged from 0.1 to 0.2 ng mg^-1 of hair.

Zr-based metal-organic framework incorporated polystyrene nanocomposite as a novel sorbent for ultrasound assisted-thin film microextraction of organophosphorus pesticides from complex samples

In this work, a novel ultrasound assisted-thin film microextraction (USA-TFME) method has been developed to determine organophosphorus pesticides (OPPs) in some fruits and vegetables samples followed by gas chromatography. In this regards, a novel nanocomposite (NC) was prepared by incorporation of zirconium-based metal-organic framework (MOF) into polystyrene (UiO-66/PS) and used as an efficient thin film. The effect of MOF doping level into UiO-66/PS NC and also the effective parameters influencing the TFME method has been studied. Based on the method validation, limits of detection were in the range of 1.5 to 3 µg kg^-1. The intra-day precision, inter-day precision and inter-sorbent precision were in the range of 5.1 to 7.2, 5.3 to 10.2 and 4.6 to 7.3 %, respectively. The developed method was prosperously applied for determination of OPPs in some fruit and vegetable samples, leading to the acceptable relative recoveries in the range of 87.8% to 96.3%.

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.

A simple, environmental-friendly and reliable d-SPE method using amino-containing metal-organic framework MIL-125-NH2 to determine pesticide residues in pomelo samples from different localities

A simple, environmentally-friendly and reliable method was developed to simultaneously monitor the residue of methyl 1-naphthalene acetate, parathion-methyl, fenitrothion, bromophos and phenthoate in pomelo by using dispersive solid-phase extraction technique (d-SPE). In this method, these target analytes were captured by MIL-125-NH₂ and detected by GC-MS/MS. The key parameters of d-SPE were optimized by the single factor experiment. Under the optimized conditions, a good determination coefficient (R² > 0.9922) and extraction recoveries (64.7-116.8%) are obtained. The limit of detections (0.03-1.07 ng/g) is lower than the MRLs in citrus fruits established by EU (10-15000 ng/g) and China (10-10000 ng/g). The precisions of intra-day and inter-day are 1.3-8.9% and 3.8-14.9%, respectively. In addition, the sorbent MIL-125-NH₂ is stable and can be reused at least eight times. These results prove the established method is efficient and reliable to detect the pesticide residues in pomelo.

Chromatographic techniques for the analysis of organophosphate pesticides with their extraction approach: a review (2015-2020)

In agriculture, a wide range of OPPs has been employed to boost crop yield, quality, and storage life. However, due to the ever-increasing population and rapid urbanization, pesticide use has surged in recent years. These compounds are exceedingly poisonous to humans, and despite the fact that specific legislation prohibits their use, the frequency of toxic and/or fatal incidents, as well as current statistics, suggest that they are currently accessible. As a result, determining the exposure to these substances as well as their detection (and that of their metabolites) in different types of exposed samples has become a hot issue in terms of quality and safety concerns. However, developing tools for the evaluation of these substances is a critical challenge for laboratories. Various chromatographic-based methods reported in the period of 2015-2020 have been developed, which are summarized and critically reviewed in this article, including the extraction of the target OPPs from different kinds of matrices. A comparison among the extraction and analysis techniques has been made in the current review article.

Ionic liquid-functionalized poly-N-phenylpyrrole coated on a NiTi alloy substrate for highly efficient solid-phase microextraction

TiO2–NiO composite nanoflakes were in situ grown, followed by electrochemical polymerization of [C4MIM]PF6@PPPy as a fiber coating for solid phase microextraction.

Investigation of five metal organic frameworks as sorbent in syringe filters-SPE method for determination of metronidazole and cephalexin in water samples

In this study, we evaluated the preparation and utilization of NH2-MIL-101(Al) and NH2-MIL-101(Cr) as two efficient adsorbents for extraction of metronidazole and cephalexin in water samples using syringe filters-SPE method....

Use of corn straw-derived biochar for magnetic solid-phase microextraction of organophosphorus pesticides from environmental samples

In this study, the potentials of utilizing corn straw-derived biochar in environmental sample pretreatment were examined. An one-step magnetization and carbonization process was developed to prepare magnetic biochar by mixing corn straw powder with Fe²⁺/Fe³⁺ and then pyrolyzed at different temperatures (400-800 °C). The obtained magnetic biochars were characterized by using scanning electron microscopy, Brunauer-Emmett-Teller isotherms, X-ray diffraction and Fourier transform infrared spectroscopy. Various extraction affecting parameters, such as Fe²⁺/Fe³⁺content, pyrolytic temperature, species of desorption solvent, extraction and desorption time, respectively, were studied and optimized. Results showed that the magnetic biochar pyrolyzed at 700 °C exhibited the best extraction performance, with enrichment factors ranging from 52 to 210, presumably due to H-bonding and π-π interactions between biochar and organophosphorus, as well as to the high surface area and pore volume of biochar. The magnetic biochar-based extraction was further combined with gas chromatography-mass spectrometry (GC/MS) to analyze trace organophosphorus pesticides from environmental samples. The method demonstrated good linearity (0.1-50 µg·L^-1), low limits of detection (0.02-0.11 µg·L^-1), and high recoveries (72.4-96.8%) from spiked water and soil samples. The results of this study suggested the promising potentials of utilizing corn straw-derived biochar for efficiently enriching trace organophosphorus pesticides from complex environmental samples.

Application of Carbonic Nanosheets Based on Urea Precursors as Dispersive Solid Phase Extraction Adsorbent for Extraction of Methamphetamine from Urine Samples

Purpose: This paper established the application of synthesized graphitic carbon nitride nanosheets (GCNNs) as an influential dispersive solid phase extraction (DSPE) adsorbent in extracting methamphetamine from complicated urine media coupled with high performance liquid chromatography.

Methods: The graphitic carbon nitride nanosheets (GCNNs) was synthesized easily and applied as adsorbent in the extraction process. The effective extraction parameters were investigated by one-parameter-at-a-time. Under optimized conditions the method was validated.

Results: The calibration curve was plotted in the concentration range of 50-1500 ng/mL through the optimized conditions and the proposed method was validated. The method was used for the analysis of positive urine samples and showed satisfactory results with the average 99.7% relative recovery.

Conclusion: The results persuade the capability of this novel method in analyzing of the positive urine samples in diverse clinical and forensic laboratories.

On the use of metal-organic frameworks for the extraction of organic compounds from environmental samples

The determination of trace metals and organic contaminants in environmental samples, such as water, air, soil, and sediment, is until today a challenging process for the analytical chemistry. Metal-organic frameworks (MOFs) are novel porous nanomaterials that are composed of metal ions and an organic connector. These materials are gaining more and more attention due to their superior characteristics, such as high surface area, tunable pore size, mechanical and thermal stability, luminosity, and charge transfer ability between metals and ligands. Among the various applications of MOFs are gas storage, separation, catalysis, and drug delivery. Recently, MOFs have been successfully introduced in the field of sample preparation for analytical chemistry and they have been used for sample pretreatment of various matrices. This review focuses on the applications of MOFs as novel adsorbents for the extraction of organic compounds from environmental samples.

Sensitive and selective determination of imidacloprid with magnetic molecularly imprinted polymer by using LC/Q-TOF/MS

In this paper, magnetic-molecularly imprinted polymer was used for the preconcentration of trace levels of imidacloprid in water and apple samples prior to liquid chromatography-quadrupole-time-of-flight mass spectrometric determination. The selectivity of the magnetic polymer was united with the sensitivity and the high resolving power of the chromatographic system. The developed method showed a linear range from 10.0 to 500.0 µg/L. The quantitative recoveries were obtained for water and apple samples in the range of 92.0%–99.0 %. The relative standard deviations of intra-day and inter-day tests were found to be in the range of 0.8%–1.2% and 1.2%–1.6 %, respectively. In addition, the same magnetic-molecularly imprinted polymer (MMIP) can be used at least ten cycles for the determination of imidacloprid. The preconcentration factor of the method was found to be 2.5, and the total preconcentration procedure can be completed in 1 h. Characterization of synthesised particles were executed with various techniques. Due to its suitable limit of detection, dynamic linear range, sensitivity and selectivity, the developed method seemed to be ideal for the determination and preconcentration of imidacloprid in water and fruit samples.

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.

Organophosphorus pesticides extraction with polyvinyl alcohol coated magnetic graphene oxide particles and analysis by gas chromatography-mass spectrometry: Application to apple juice and environmental water

In this study, we synthesized, characterized the magnetic graphene oxide coated with polyvinyl alcohol (PVA@MGO), and used it as an adsorbent for the magnetic solid-phase extraction (MSPE) of organophosphorus pesticides (OPPs) residue in the apple juice and environmental water samples followed by gas chromatography-mass spectrometry (GC-MS) analysis. Effective factors on the extraction efficiency, including the adsorbent dosage, desorption conditions, sample pH, extraction and desorption time, and ionic strength were optimized. The dynamic range of the MSPE-GC-MS method was obtained in the concentration range of 0.07-500 ng mL^-1 OPPs with the limits of detection (LODs) in the range of 20-80 pg mL^-1. Also, the intra- and inter-day precisions were determined to be in the range of 3.3-5.7% and 5.9-8.2%. The relative recoveries of pesticides for spiked real water samples and apple juice were in the range of 94.5 and 107.1%, with relative standard deviations between 2.6 and 6.5%. These results propose that the PVA@MGO is appropriate for simultaneous determination and high throughput analysis of OPPs residues.

Metal-organic frameworks for food applications: A review

Metal-organic frameworks (MOFs) are high surface-to-volume ratio crystalline hybrid porous coordination materials composed of metal ions as nodes and organic linkers. The goal of this paper was to provide an updated and comprehensive state-of-the-art review of MOFs for different food applications such as active food contact materials, antimicrobial nanocarriers, controlled release nanosystems for active compounds, nanofillers for food packaging materials, food nanoreactors, food substance nanosensors, stabilizers and immobilizers for active compounds and enzymes, and extractors of food contaminants. Extraction and sensing of several food contaminants have been the main food applications of MOFs. The other applications listed above require further investigation, as they are at an early stage. However, interesting results are being reported for these other fields. Finally, an important limitation of MOFs has been the use of non-renewable feedstocks for their synthesis, but this has recently been solved through the manufacture and use of γ-cyclodextrin-based MOFs.

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.

Customized dispersive micro-solid-phase extraction device combined with micro-desorption for the simultaneous determination of 39 multiclass pesticides in environmental water samples

A dispersive micro-solid phase extraction (d-µ-SPE) procedure was developed for the simultaneous extraction of 39 multiclass pesticides, containing a variety of chemical groups (organophosphate, organochlorine, pyrethroid, strobilurin, thiocarbamate, triazole, imidazole, and triazine), from water samples. A customized d-µ-SPE glass device was combined with a multi-tube platform vortex and a micro-desorption unit (Whatman Mini-UniPrep G2 syringeless filter), which allowed the unique simultaneous desorption, extract filtration, and injection. A simplex-centroid mixture design and Doehlert design were employed to optimize the extraction conditions. The optimized extraction conditions consisted of an extraction time of 30 min, an addition of 6.74 % of NaCl into 100 mL of water sample, and a desorption time of 24 min with 500 µL of EtAc. The procedure provided a low limit of detection (LOD), ranging from 0.51 ng L^-1 (4,4-DDE) to 22.4 ng L^-1 (dimethoate), and an enrichment factor ranging from 72.5 (dimethoate) to 200 (tebuconazole). The relative recoveries of the pesticides from spiked freshwater and seawater ranged from 74.2 % (endrin) to 123 % (molinate). The proposed procedure was applied to detect the presence of multiclass pesticides in environmental water samples. Three pesticides commonly applied in Brazil, namely, malathion, dimethoate, and lambda-cyhalothrin, were detected in concentrations ranging from <LOD to 120 ng L^-1 (dimethoate).

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.