Metal organic frameworks enhanced dispersive solid phase microextraction of malathion before detection by UHPLC‐MS/MS

Fixed-bed adsorption studies of endocrine-disrupting compounds from water by using novel calcium-based metal-organic frameworks

The presence of emerging water pollutants such as endocrine-disrupting compounds (EDCs), including 17-ethynylestradiol (EE2), bisphenol A (BPA), and perfluorooctanoic acid (PFOA), in contaminated water sources poses significant environmental and health challenges. This study aims to address this issue by investigating the efficiency of novel calcium-based metal-organic frameworks, known as mixed-linker calcium-based metal-organic frameworks (Ca-MIX), in adsorbing these endocrine-disrupting compounds. This study analyzed the influence of influent concentration, bed height, and flow rate on pollutant removal, with bed height emerging as a crucial factor. From the breakthrough curves, it was determined that the column maximum adsorption capacities followed the order of 17-ethynylestradiol (101.52 μg/g; 40%) > bisphenol A (99.07 μg/g; 39%) > perfluorooctanoic acid (81.28 μg/g; 32%). Three models were used to predict the adsorption process, with the Yan model outperforming the other models. This suggests the potential of mixed-linker calcium-based metal-organic frameworks for removing endocrine-disrupting compounds from water, using the Yan model as an effective predictor. Overall, this study provides valuable insights for the development of effective water treatment methods using mixed-linker calcium-based metal-organic frameworks to remove endocrine-disrupting compounds from contaminated water sources.

Green, mildly synthesized bismuth-based MOF for extraction of polar glucocorticoids in environmental water

The complex sample matrix and low environmental concentration make it challenging to effectively determine the polar glucocorticoids. In particular, a green, economical, and environmentally friendly method is urgently needed, since a large amount of extraction solvents, samples, and extraction materials have been commonly used to improve the sensitivity of the reported methods. In this study, a green and robust phenol and bismuth-based MOF of SU101 was mildly synthesized and fabricated as a brand new solid-phase microextraction (SPME) fiber. Only tiny amounts of SU101 and desorption solvents were employed to realize the high-efficiency enrichments of glucocorticoids from water samples. The detection performance of proposed SU101 fiber towards glucocorticoids was much superior to the single-component and multi-component commercial fibers. It indicated that SU101 fiber could be an excellent candidate for the enrichments of polar pharmaceuticals. After it was coupled with the instrument of high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS), the linear range of 5-10000 ng L-1 with detection limits low to 0.070-1.5 ng L-1 and satisfactory recoveries were achieved by the developed method. Benefiting from the environmental friendliness of SU101 and the less-solvent consumption of SPME technique, this work presented a green and economical strategy for determinations of trace glucocorticoids.

ZIF67-derived porous carbon-reinforced electrospun nanofiber as an extractive phase for on-chip micro-solid-phase extraction of antifungals from biological fluids prior to liquid chromatography tandem mass spectrometry

With a view to improving applicability as a sorbent while overcoming the challenges associated with its powdery nature, cobalt-doped zeolitic imidazolate framework (ZIF 67)-derived nanoporous carbon (Co-NPC) was employed as an additive in nanofiber through the process of electrospinning. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and Brunauer-Emmett-Teller (BET) surface area analysis were used to characterize the resulting nanocomposite. A microfluidic chip device with four layers, including two layers entailing spiral channels, was designed and employed to assess the analytical performance of the fabricated Co-NPC-reinforced electrospun composite. To do so, a folded piece of electrospun composite was sandwiched between two layers with spiral channels. Therefore, both sides of the folded composite acted as a sorptive phase to extract antifungal drugs as target analytes. The significant factors affecting the efficiency of the extraction process were investigated and optimized. Subsequently, the technique was verified through the utilization of liquid chromatography-tandem mass spectrometry (LC-MS/MS) by employing optimal parameters. The optimal conditions were applied to evaluate the figures of merit. A linear range was obtained for antifungal drugs within the range 0.25-200.0 ng ml-1 with an R2 value of ≥ 0.9914. The method demonstrated detection limits ranging between 0.08 and 0.40 ng ml-1. The intra-day and inter-day precisions were less than 6.9%. Relative recoveries exhibited variations between 91.4-106.8%, 95.9-103.6%, and 96.4-109.3% for ketoconazole, clotrimazole, and miconazole, respectively. The proposed approach yielded satisfactory results, demonstrating its efficiency.

Simultaneous derivatization and extraction of amphetamine and methamphetamine using dispersive liquid-liquid microextraction prior to their analysis using GC-FID in creatine supplements

This study was focused on the development of a sensitive, reliable, and efficient extraction procedure for the determination of amphetamine and methamphetamine utilized in the adulteration of creatine sports supplements. The separation and detection of the analytes were conducted using the gas chromatography-flame ionization detection method. In this study, the analytes were extracted from a supplement powder into a proper solvent by sonication. Then, the extract was mixed with butyl chloroformate to obtain their butylated derivatives and then concentrated by a dispersive liquid-liquid microextraction procedure. The method was performed in a short time. Under optimized extraction conditions, a linear range of 2.01-500 ng g-1 was obtained by a coefficient of determination ≥0.996. Low detection (0.22 ng g-1 and 0.61 ng g-1 for amphetamine and methamphetamine, respectively) and quantification (0.73 ng g-1 and 2.01 ng g-1 for amphetamine and methamphetamine, respectively) limits, good precision (relative standard deviations ≤8.2%), and high extraction recoveries (79% and 86% for amphetamine and methamphetamine, respectively) were achieved. The usefulness of the method in the analysis of the target compounds was confirmed by studying the matrix effect and analysis of the analytes in different real samples.

Keggin-type polyoxometalate embedded polyvinylidene fluoride for thin film microextraction of organophosphorus pesticides

The present research is the first report on the application of Keggin-type phosphotungstic acid/polyvinylidene fluoride membrane. This compound as a simple, cost-effective and novel sorbent was used for the extraction and pre-concentration of two organophosphorus pesticides in real samples in the thin film solid-phase microextraction (TFME) method. TFME as one of the sub-branches of solid phase microextraction resolves the problems of SPME methods, including their limited absorption capacity. These extraction methods have a high surface-to-volume ratio, which improves their sensitivity compared to other geometries. Under optimal conditions, the limit of detections (LODs), the limit of quantifications (LOQs), and relative standard deviation (RSD) of this method varied in the ranges of 0.29-0.31 μg L-1, 0.96-1.0 μg L-1, and 3.9%-6.2%, respectively. This method showed a linear dynamic range (LDR) of 1.0-500 μg L-1 with a coefficient of determination (r2) above 0.9978. This promising method was used to analyze malathion and diazinon.

Facile synthesis of novel magnesium oxide nanoparticles for pesticide sorption from water

The quantum of pesticides in surface as well as drinking water has become a serious health hazard. In this experiment, magnesium oxide nanoparticles (MgO NPs) were synthesized using leaves of purple-colored rice variety (Crossa) and utilized for simultaneous removal of three pesticides, namely, thiamethoxam, chlorpyriphos, and fenpropathrin from water. The biogenic MgO NPs were characterized using SEM-EDX, FTIR, XRD, DLS, etc. The optimum synthesis parameters (1 M NaOH, 80 °C, and 2 h) resulted in maximum yield of MgO NPs (87.7 mg), minimum hydrodynamic diameter (35.12 nm), poly dispersity index (0.14) and mean zeta potential (-11 mV). Sorption data of the three pesticides fitted well with non-linear Langmuir and Freundlich isotherm models and non-linear pseudo-second-order kinetic model. The maximum adsorption capacity of MgO NPs for the three pesticides was 87.66 µg/mg, as obtained from the Langmuir isotherm model. Under optimum conditions (initial concentration, 40 mg/L; dose, 30 mg/30 mL; and pH, 9), 60.13, 80.53, and 92.49% removal of thiamethoxam, chlorpyriphos, and fenpropathrin was achieved with a 100% desirability, respectively. Thus, the biogenic MgO NPs could be an efficient adsorbent of pesticides and could be recommended for pesticide decontamination in water treatment plants and domestic water purifier systems.

Polyaniline-co-polyindole functionalized magnetic porous carbon derived from MIL-53(Fe) for separation/enrichment of nitrophenols pollutants before determination with high-performance liquid chromatography-ultraviolet detection

Herein, a novel polyaniline-co-polyindole functionalized magnetic porous carbon derived from MIL-53(Fe) was prepared and employed as an excellent nano-adsorbent to preconcentrate trace amounts of nitro-phenols in water and wastewater samples. Briefly, magnetic MIL-53(Fe) was synthesized by the addition of magnetite nanoparticles, terephthalic acid, and FeCl3 to the reaction medium. The magnetic MIL-53(Fe) was pyrolyzed under nitrogen protection to obtain a magnetic porous carbon nanocomposite, and finally, the nanomaterial was functionalized with polyaniline-co-polyindole via oxidation polymerization. The obtained nano-adsorbent was characterized via X-ray diffraction, Fourier-transform infrared spectroscopy, vibrating sample magnetometry, and transmission and scanning electron microscopies. After that, the fabricated nano-material was utilized as an excellent nano-adsorbent for the preconcentration of trace nitro-phenols (2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol) in environmental water, and wastewater samples. The detection limits were obtained from 0.1 to 0.15 μg/L after performing the optimization process. The new method was in the range of 0.4-300 μg/L. The proposed method exhibited a good precision from 3.2% to 9.6% for within-day assay, and 5.2%-13.2% for between-day assay at three concentration levels (1, 50, and 250 μg/L). Eventually, this method was utilized to preconcentrate/determine the target analytes in three water, and wastewater samples, satisfactory (relative standard deviations, 5.4%-9.3%; relative recovery, 88%-109%).

Advanced Development of Molecularly Imprinted Membranes for Selective Separation

Molecularly imprinted membranes (MIMs), the incorporation of a given target molecule into a membrane, are generally used for separating and purifying the effective constituents of various natural products. They have been in use since 1990. The application of MIMs has been studied in many fields, including separation, medicine analysis, solid-phase extraction, and so on, and selective separation is still an active area of research. In MIM separation, two important membrane performances, flux and permselectivities, show a trade-off relationship. The enhancement not only of permselectivity, but also of flux poses a challenging task for membranologists. The present review first describes the recent development of MIMs, as well as various preparation methods, showing the features and applications of MIMs prepared with these different methods. Next, the review focuses on the relationship between flux and permselectivities, providing a detailed analysis of the selective transport mechanisms. According to the majority of the studies in the field, the paramount factors for resolving the trade-off relationship between the permselectivity and the flux in MIMs are the presence of effective high-density recognition sites and a high degree of matching between these sites and the imprinted cavity. Beyond the recognition sites, the membrane structure and pore-size distribution in the final imprinted membrane collectively determine the selective transport mechanism of MIM. Furthermore, it also pointed out that the important parameters of regeneration and antifouling performance have an essential role in MIMs for practical applications. This review subsequently highlights the emerging forms of MIM, including molecularly imprinted nanofiber membranes, new phase-inversion MIMs, and metal-organic-framework-material-based MIMs, as well as the construction of high-density recognition sites for further enhancing the permselectivity/flux. Finally, a discussion of the future of MIMs regarding breakthroughs in solving the flux-permselectivity trade-off is offered. It is believed that there will be greater advancements regarding selective separation using MIMs in the future.

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%).

Rapid extraction of BTEX in water and milk samples based on functionalized multi-walled carbon nanotubes by dispersive homogenized-micro-solid phase extraction

An advanced synthesis based on the phenylalanine (Phe) and task-specific ionic liquid (TSIL) functionalized on multi-walled carbon nanotubes (Phe/TSIL@MWCNTs), was used to extract benzene, ethylbenzene, toluene, and xylene (BTEX) from cow's milk, powdered milk, and farm water samples. The BTEX was efficiently extracted by ultrasound-assisted dispersive homogenized-micro-solid phase extraction (USA-DH-µ-SPE) between 95.1% and 103.4%. By procedure, 50 mg of Phe/TSIL@MWCNTs was added to 0.2 mL of acetone and injected into 10 mL of the samples. The upper aqueous solution was vacuumed, the vial heated to 80 °C, and the BTEX desorbed in the vial. Then, using a Hamilton syringe, 1-20 µL of gas in the headspace vial was determined by injecting it into the gas chromatography with flame ionization detection (GC-FID). The linear range, LOD, and LOQ for BTEX in milk and water samples were obtained at 0.05-500 µg L^-1, 15 ng L^-1, and 50 ng L^-1, respectively (r = 0.9997, RSD% = 2.27).

An all-embracing analytical method comprising modified QuEChERS-dispersive micro-solid-phase extraction-dispersive liquid-liquid microextraction using FeGA MOF for the extraction and preconcentration of pesticides simultaneously from juice and flesh of watermelon

For the first time, a comprehensive analytical method based on a one-dimensional metal-organic framework comprising "quick, easy, cheap, effective, rugged, and safe-dispersive micro solid phase extraction-dispersive liquid-liquid microextraction" was introduced in this research. Moreover, the first-ever attempt was accomplished to apply the iron-gallic acid metal-organic framework in analytical method development. The goal of the research was to analyze the pesticide content of watermelon comprehensively in its flesh and juice. Based on this, comprehensive and reliable food safety monitoring can be done. Initially, pesticides of the watermelon flesh were extracted using an mL volume of acetonitrile by vortexing. At the same time, the pesticides of watermelon juice were extracted from the juice matrix onto the sorbent particles facilitated by vortexing. The obtained acetonitrile phase was also used to desorb the analytes from the sorbent surface by vortexing. As a result, the pesticide content of both juice and flesh was extracted into the acetonitrile. The pesticide-enriched acetonitrile was then used as the disperser solvent by being merged with µL level of 1,2-dibromoethane and injection into deionized water. A cloudy solution was created as the result. Centrifugation triggered extractant at the bottom of the conical glass test tube and an aliquot of it was injected into a gas chromatograph equipped with a flame ionization detector. High enrichment factors (210-400), appreciable extraction recoveries (42-80%), wide linear ranges (3.20-1000 µg kg^-1), relative standard deviations in the ranges of 3.6-4.4% for intra- (n = 6) and 4.4-5.3% for inter-day (n = 3) precisions, and low limits of detection (0.43-0.97 µg kg^-1), and quantification (1.42-3.20 µg kg^-1) were obtained by the application of the developed method.

Removal of fenamiphos, imidacloprid, and oxamyl pesticides from water by microalgal Nannochloropsis oculata biomass and their determination by validated HPLC method

The present study assessed the removal of fenamiphos, imidacloprid, and oxamyl pesticides from water using algal Nannochloropsis oculata biomass. Several factors, such as algal biomass concentration, incubation time, and pesticide concentration, were studied for their impact on pesticide removal. Analysis and quantification of pesticides by rapid HPLC have been developed and validated. The optimum conditions were obtained at 15 min, 50 mg/L of pesticide concentration, and 4,500 mg/L of the algal biomass with 92.24% and 90.43% removal for fenamiphos and imidacloprid, respectively. While optimum parameters of 10 min incubation, 250 mg/L of pesticide concentration, and 2,750 mg/L of the algal biomass exhibited 67.34% removal for oxamyl. N. oculata, marine microalgae, successively removed different concentrations of the tested pesticides from water, and the algal biomass showed a potential reduction of pesticides in polluted water samples.

Ameliorating SERS Sensitivity for Pesticide Malathion Detection with Synergistic Boosting Effect by Hydrogen Cations and Chloride Anions

Although SERS has been widely recognized as one of the highly sensitive analytical methods that can be deployed in the field with high sensitivity and short analysis time, reports regarding the fast determination of malathion at low concentrations are still scarce. Here, in this work, the solution pH and various halogen co-adsorbates were explored to promote the SERS signal of malathion using the citrate-reduced Ag NPs. It was found that chloride anions were the most efficient signal booster among the three halogen ions screened. Further examination of the SERS profile of the malathion in the presence of different halogen species found that the stretching mode of the P-S bond shifted to a lower frequency with Cl^-, which may imply closer (and stronger) binding of malathion to the Ag NPs. This concurs with literature reports that halogen ions could facilitate the adsorption of a certain analyte onto the SERS substrate. In addition, hydrogen ions showed a synergistic effect on SERS signal enhancement when combined with chloride anions. At optimum conditions, the malathion could be detected with a limit of detection (LOD) of 3 ppb. Malathion-spiked cherry tomatoes and oranges were analyzed, and the recovery rates were found to be within 85-100%.

Microextraction of organophosphorus pesticides on a screw coated with PAN/calcined ZnMgAl-LDH electrospun nanofibers

The present research is an attempt to expand the recently reported microextraction on screw method. For this purpose, polyacrylonitrile/calcined ZnMgAl-LDH nanofiber was fabricated by the electrospinning technique on the surface of a screw. It was applied to the extraction of organophosphorus pesticides (OPP) from agricultural samples. The separation and determination of OPPs were carried out by gas chromatography-mass spectrometry. The characterization of the fabricated nanofiber was performed utilizing Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction instruments. Effective parameters on the extraction efficiency of the analytes including sample pH, ionic strength, sample flow rate and number of cycles, type, volume, and flow rate of desorption solvent were optimized by one-variable-at-a-time method. Under optimized conditions, the limits of detection were 0.03 and 0.07 μg L^-1 for diazinon and chlorpyrifos, respectively. This method showed wide linearity in the range 0.10-1000 μg L^-1 for diazinon and 0.25-1000 μg L^-1 for chlorpyrifos with R² > 0.996. The intra- and inter-day precisions (RSD%, n = 3) were ≤ 6.4% and ≤ 7.7%, respectively. Also, RSD% values less than 11.1% were obtained for screw-to-screw reproducibility. The applicability of the method for the extraction and determination of the analytes in complex agricultural environments such as cabbage, potato, tomato, cucumber, and beetroot was investigated. The results led to acceptable relative recoveries in the range 81.0-108.2%.

Functionalized MOF as a Sensitive Spectroscopic Probe for Hg2+, Co2+, and Al3+ Ions Detection in Aqueous Media

A modified metal-organic framework (MOF) named Al-MIL-53-N=SA-Br was synthesized via a Schiff-base reaction between the MOFs (Al-MIL-53-NH₂) and 5-bromo salicylaldehyde. The robust functionalized Al-MIL-53-N=SA-Br was used as a novel spectrophotometric sensor for detecting Hg²⁺, Co²⁺, and Al³⁺ ions. In a wide range of concentrations, the absorption spectral intensity of Al-MIL-53-N=SA-Br increased linearly upon increasing the concentration of Hg²⁺, Co²⁺, and Al³⁺ ions. The limit of detection (LOD) of the proposed Al-MIL-53-N=SA-Br sensor reached 1.52 ppm of Hg²⁺ ion (7.56 × 10^-9 M). Therefore, this study introduces a novel ratiometric Hg²⁺, Co²⁺, and Al³⁺ ions chemosensor. Simple treatment using thiourea or ethylenediaminetetraacetic acid can remove the metal ions from the used sensor and use it many times with a high efficiency. In addition, the Al-MIL-53-N=SA-Br sensor has a high adsorption capacity for these metal ions. The design of the robust Al-MIL-53-N=SA-Br sensor provided high stability, reproducibility, selectivity, high sensitivity, and a facile sensing design. Furthermore, the good absorption spectral stability of Al-MIL-53-N=SA-Br in aqueous media, the broad linear in sensing, and the low LOD of the Hg²⁺, Co²⁺, and Al³⁺ ions show its high potential in determining these ions in real water.

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.

Pyridine ionic liquid functionalized bimetallic MOF solid-phase extraction coupled with high performance liquid chromatography for separation/analysis sunset yellow

An effective method based on the pyridine ionic liquid functionalized bimetallic MOF solid-phase extractant (Cu/Co-MOF@[PrPy][Br]) coupled with high performance liquid chromatography (HPLC) for the separation/analysis sunset yellow was established. Cu/Co-MOF@[PrPy][Br] was characterized by FTIR, XRD, SEM and TEM. Several important factors, such as pH, amount of extractant, extract time, and types of eluents were investigated in detail. Under the optimal conditions, linear range of the method was 0.05–40.00 μg mL⁻¹, the detection limit was 0.02 μg mL⁻¹, and the linear correlation was good (R² = 0.9992). The analysis of sunset yellow in soda, effervescent tablet and jelly proved that the method was simple and effective.

An effective method based on the pyridine ionic liquid functionalized bimetallic MOF solid-phase extractant (Cu/Co-MOF@[PrPy][Br]) coupled with high performance liquid chromatography (HPLC) for the separation/analysis sunset yellow was established.

Development of poly(vinyl alcohol)/chitosan/aloe vera gel electrospun composite nanofibers as a novel sorbent for thin-film micro-extraction of pesticides in water and food samples followed by HPLC-UV analysis

Schematic presentation of applying PVA/CA/CS/AV composite nanofibers as the extraction phase in thin-film micro-extraction (TFME) of six pesticide compounds prior to HPLC-UV analysis.

Remarkable adsorption of hydroquinone as an anion contaminant by using the magnetic supported bimetallic (NiCu-MOF@MAC) nanocomposites in aqueous solutions

The purposes of this work were to synthesize the core-shell magnetic and nonmagnetic supported bimetallic metal-organic frameworks (MOFs) on the walnut-based activated carbon by the facile preparation method to investigate the feasibility of the performance adsorption of hydroquinone in the aqueous solutions. Activated carbon as a substrate and nickel, copper, and trimesic acid were employed in the structure of the prepared MOFs. The adsorbents were characterized by XRD, FTIR, FESEM, EDX, TEM, BET, and VSM analysis. The goethite and magnetite phases were detected in the morphology of the magnetic adsorbent as confirmed by the XRD pattern. Increases in the pH value from 6 and the adsorption temperature led to a lower adsorption capacity of the samples. The maximum adsorption capacity for the well-dispersed nanoparticles of magnetic (NiCu-MOF@MAC and nonmagnetic (NiCu-MOF@AC) was calculated to be 303.03 and 454.54 mg/g by using linear Langmuir isotherm as an appropriate model, respectively. The achievements from the reusability evaluation illustrated that the magnetic bimetallic MOF nanocomposite could successfully be applied to remove hydroquinone from the wastewater on an industrial scale. The kinetic experimental data was in good agreement with the pseudo-second-order model.

Accelerated FeIII/FeII redox cycle of Fenton reaction system using Pd/NH2-MIL-101(Cr) and hydrogen

In this paper, a novel improvement in the catalytic Fenton reaction system named MHACF-NH₂-MIL-101(Cr) was constructed based on H₂ and Pd/NH₂-MIL-101(Cr). The improved system would result in an accelerated reduction in Fe^III, and provide a continuous and fast degradation efficiency of the 10 mg L^-1 4-chlorophenol which was the model contaminant by using only trace level Fe^II. The activity of Pd/NH₂-MIL-101(Cr) decreased from 100% to about 35% gradually during the six consecutive reaction cycles of 18 h. That could be attributed to the irreversible structural damage of NH₂-MIL-101(Cr).

Determination of pyridaphenthion in soybean sprout samples by gas chromatography mass spectrometry with matrix matching calibration strategy after metal sieve linked double syringe based liquid-phase microextraction

A novel analytical strategy for the trace determination of pyridaphenthion pesticide was developed in this study. Gas chromatography-mass spectrometry (GC-MS) was used for the accurate, feasible and precise determination of this analyte. Liquid phase microextraction (LPME) was performed with a metal sieve linked double syringe (MSLDS) system, which eliminated the need for a disperser solvent. In order to increase extraction efficiency for the analyte, all variable parameters were optimized and the system analytical performance of the proposed method was determined. Limit of detection and quantification (LOD and LOQ) values of pyridaphenthion were found to be 0.8 and 2.7 µg L-1, respectively. Compared to GC-MS system's analytical performance, the developed method provided approximately 273-folds improvement in the detection limit of the analyte. Applicability/accuracy of the developed analytical strategy was checked by recovery experiments carried out with soybean sprouts, and the results obtained were satisfactory.

New Trend in the Extraction of Pesticides from the Environmental and Food Samples Applying Microextraction Based Green Chemistry Scenario: A Review

This review focused on the green microextraction methods used for the extraction of pesticides from the environmental and food samples. Microextraction techniques have been explored and applied in various fields of analytical chemistry since its beginning, as evinced by the numerous reviews published. The success of any technique in science and technology is measured by the simplicity, environmentally friendly, and its applications; and the microextraction technique is highly successive. Deliberations were attentive to studies where efforts have been made to validate the methods through the inter-laboratory comparison study to assess the analytical performance of microextraction techniques against conventional methods. Succinctly, developed microextraction methods are shown to impart significant benefits over conventional techniques. Provided that the analytical community continues to put forward attention and resources into the growth and validation of the microextraction technique, a promising future for microextraction is forecasted.

Applications of porous frameworks in solid-phase microextraction

Porous frameworks are a term of attracting solid materials assembled by interconnection of molecules and ions. These trendy materials due to high chemical and thermal stability, well-defined pore size and structure, and high effective surface area gained attention to employ as extraction phase in sample pretreatment methods before analytical analysis. Solid-phase microextraction is an important subclass of sample preparation technique that up to now different configurations of this method have been introduced to get adaptable with different environments and analytical instruments. In this review, theoretical aspect and different modes of solid-phase microextraction method are investigated. Different classes of porous frameworks and their applications as extraction phase in the proposed microextraction method are evaluated. Types and features of supporting substrates and coating procedures of porous frameworks on them are reviewed. At the end, the prospective and the challenges ahead in this field are discussed.