Desorption Solvent Volume Research Articles

Fe3O4@UiO-66-NH2 based on magnetic solid phase extraction for determination of organic UV filters in environmental water samples

In this work, a nanocomposite structured magnetic metal–organic framework named as Fe3O4@UiO-66-NH2 was prepared via a simple hydrothermal approach. The as-mentioned nanocomposite was characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and the Brunauer–Emmett–Teller (BET) techniques. Using the Fe3O4@UiO-66-NH2 as a nanosorbent, an easy and highly effective approach was developed to preconcentrate nine organic UV filters before gas chromatography–mass spectrometry (GC–MS) analysis. Different conditions influencing the extraction efficiency encompassing the sorbent amount, nature and volume of desorption solvent, desorption time, pH of the sample, and extraction time, were examined. Under the optimal experimental parameters, the Fe3O4@UiO-66-NH2-based magnetic solid phase extraction and GC–MS (MSPE–GC–MS) demonstrated linearity in the range of 0.03–1500 ng/L (R2 ≥ 0.9974) and the reproducibility, expressed as RSD, was ≤7.5%. The limits of detection ranged between 0.01 and 0.07 ng/L and limits of quantification were in the range of 0.03–0.4 ng/L. Finally, the suggested approach was satisfactorily utilized to determine nine organic UV filters in different water samples (analytical recoveries between 86.5% and 104.2%).

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%.

Green hydrophobic maltodextrin nanosponges for magnetic solid-phase extraction of hypothalamic peptides from plasma samples

In this work, for the first time, magnetic-phthalated maltodextrin nanosponges (M-PAMDNSs) were synthetized and introduced as efficient and green sorbents. The integration of phthaloyl groups as hydrophobic moieties into networks of maltodextrin nanosponges provided good enrichment for hypothalamic-related peptides (HRPs). The synthesized materials were characterized by 1H nuclear magnetic resonance spectroscopy, water contact angle, attenuated total reflection-Fourier transform infrared spectroscopy, dynamic light scattering, zeta potential, pH point of zero charge, acid-base titration, field-emission scanning electron microscopy, Brunauer-Emmett-Teller, and vibrating sample magnetometer. Under the optimized conditions (sorbent amount: 5.0 mg, desorption solvent volume and type: 300 µL of methanol: H2O: trifluoroacetic acid, extraction time: 15 min, and desorption time: 10 min), the developed magnetic solid-phase extraction (MSPE) method in combination with HPLC-UV was used as a novel and sensitive analytical method for the determination of HRPs in plasma samples. The proposed MSPE-HPLC-UV method provided good linearity (1.5–500 ng mL−1 R2 ≥ 0.9988), low limits of detection (0.1–0.2 ng mL−1) and quantification (0.4–0.8 ng mL−1), desirable precision (RSD ≤ 8.8%, n ₌ 5), satisfactory enrichment factor (EFs ≥ 66.0), and well relative recoveries (92.8–108.8%). Overall, the established method effectively expanded the analytical potential of MSPE approach for the quantification of HRPs in biological samples.

Simple and selective extraction of quercetin with microextraction in packed syringe method using modified glass powder by a molecularly imprinted polymer followed by spectrophotometric determination.

A new sample preparation method based on microextraction in packed syringe was developed for preconcentration of quercetin prior to its spectrophotometric determination. Molecularly imprinted polymers as packing material was used for higher extraction efficiency. First, glass powder as support material because of low cost and available substrate was modified, and then molecularly imprinted polymers were synthesized by the sol-gel method using 3-aminopropyltriethoxysilane as a functional monomer and tetraethyl orthosilicate as cross-linker agent. The combination of a molecularly imprinted polymers and microextraction in packed syringe increased the selectivity and sensitivity. The surface morphology and functionality of the prepared molecularly imprinted polymers was characterized using Fourier-transform infrared spectroscopy, Field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, and thermogravimetric analysis. Different influencing parameters on extraction efficiency such as effect of the number of sample sorption/desorption cycles, type and volume of desorption solvent, pH of the sample solution, and molecularly imprinted polymers amounts were optimized. Under the optimum condition, the proposed method displayed a linear range from 0.01 to 5µg mL-1 and limit of detection 3.68ng mL-1 . Relative standard deviation for three replicate determination of 1µg mL-1 quercetin was 2.1 %. The proposed method was applied successfully for the selective extraction of quercetin from tea and coffee samples.

Determination of bupropion by off-line coupling Fe3O4@CuO&GO nanocomposite and ion mobility spectrometry with application to biological samples.

In this study, an off-line coupling of dispersive solid-phase extraction (DSPE) and ion mobility spectrometry (IMS) was introduced to extract and determine bupropion (BUP). A magnetic nanocomposite adsorbent (Fe3O4@CuO&GO) was fabricated by combining graphene oxide (GO) sheets with Fe3O4 and CuO through coprecipitation method. The synthesized adsorbent was characterized and analyzed using the analytical techniques. The effect of extraction parameters including desorption solvent (type and volume), pH, adsorbent amount, contact time, temperature, and the volume of analyte solution on the extraction efficiency was investigated and optimized. The operational parameters of IMS method were also investigated. Under the optimum conditions (DSPE-IMS), the proposed method provided a linear range 4.0-24.0ng for BUP with a determination coefficient R2 ≥ 0.98. LOD and LOQ values were 0.7 and 2.2ng for BUP. The repeatability of proposed method was evaluated and reported as relative standard deviation (RSD% ≤ 5.5). The developed method was applied to determine BUP in different biological samples, in which satisfactory results were obtained (93.0-98.0%).

Green dispersive solid-phase microextraction of melamine using crosslinked beta-cyclodextrin with citric acid followed by high-performance liquid chromatography.

In this research, a green approach for dispersive solid phase microextraction was introduced for the extraction and determination of melamine in various matrices such as infant formula and hot water in a melamine bowl. In this way, a natural polar polymer called ß-cyclodextrin has been cross-linked with citric acid to create a water-insoluble adsorbent. The extraction was carried out by dispersion of the sorbent into the sample solution. The effective parameters on the extraction efficiency of the melamine, including ion strength, extraction time, sample volume, amount of absorbent, pH, type of desorption solvent, desorption time, and desorption solvent volume were optimized by one variable at a time approach. Under the optimal conditions, the method showed a good linear dynamic range for melamine in the range of 1-1000μg/L with a coefficient of determination of 0.9985. The obtained limit of detection was 0.3μg/L. The intra-day and inter-day relative standard deviations (n=3) were 3.1% and 3.2% respectively. Lastly, this technique was applied to extract and determine the analyte in a melamine bowl and infant formula with acceptable and satisfactory results.

3D printed solid phase microextraction scaffolds as novel tool for sample preparation; application in antifungal drugs analysis

3D printed solid phase microextraction scaffolds as a novel sorbent were introduced for the extraction of antifungal drugs in wastewater and human plasma prior to their determination by HPLC-UV. The designed adsorbent was prepared as cubic scaffolds using fused deposition modeling (FDM) 3D printer and Polylactic acid (PLA) filament. Scaffold surface was chemically modified using alkaline ammonia solution (Alkali treatment). The application of this new design in the extraction of three antifungal drugs ketoconazole, clotrimazole and miconazole was investigated. Alkali surface modification time was optimized (0.5-5hr) and 4hr selected as the best-modification time. Morphology of the modified surface and its chemical changes were studied using Field Emission Scanning Electron Microscope (FE-SEM) and Attenuated Total Reflectance Fourier Transform Infrared spectroscopy (ATR-FTIR), respectively. Surface wettability of scaffolds was measured by Water Contact Angel (WCA) and the porosity created in the scaffolds was studied by N2 adsorption/desorption studies analysis. Analytical performance of the method, under optimum conditions (extraction time: 25 min, desorption solvent: methanol, volume of desorption solvent: 2 mL, desorption time: 10 min, solution pH: 8, solution temperature: 40 °C, salt concentration: 3 mol L−1) were obtained as 3.10 and 10.0 µg L−1 for LOD and LOQ, respectively. The calibration graphs were linear in the range of 10–150 µg L−1 and 10-100 µg L−1 for wastewater and plasma, respectively.

Solid Phase Extraction Penicillin and Tetracycline in Human Serum Using Magnetic Graphene Oxide-Based Sulfide Nanocomposite

Herein, we report a procedure for separating and preconcentrating antibiotics from human serum using a novel adsorbent of magnetic graphene oxide (MGO) and cadmium sulfide (CdS) nanoparticles. The adsorbent (MGO@CdS) was characterized using Fourier transformed infrared spectrometry (FT-IR), energy dispersive X-ray spectroscopy (EDX), and field emission scanning electron microscopy (FE-SEM). The effective parameters for extraction efficiency were investigated, including the desorption solvent’s nature, pH, adsorbent dose, salt concentration, extraction time, and volume of sample solution and desorption solvent. The proposed procedure proved to be fast (20 min), simple (two stages), and cost-effective (20 mg of nanoparticles). Under the optimum conditions, satisfactory linearity (R2 > 0.992) was obtained, and limits of detection (LOD) were estimated as 4.5 µg L−1 (for tetracycline) and 5.7 µg L−1 (for penicillin) and a linear dynamic range (LDR) from 20 to 200 µg L−1. The magnetic solid phase extraction (MSPE) method based on MGO@CdS has achieved a satisfactory recovery (71.5–109.5%) in human serum for the selected antibiotics. Finally, the antibiotic’s release was studied in simulated fluids of the gastric (pH = 1.2) and intestine (pH = 7.4). In this light, we demonstrate that the newly introduced adsorbent can be used in drug extraction from different biological media.

Magnetic carbonized cellulose-MIL 101(Fe) composite as a sorbent for magnetic solid phase extraction of selected organophosphorus pesticides combined with high performance liquid chromatography-ultraviolet detection

In this research project, an attempt was made to synthesize new composite based on nanomaterials and use these materials to improve the performance of magnetic solid phase extraction for the extraction of some selected organophosphorus pesticides in real samples. Therefore, the metal-organic framework MIL-101 was grown by layer-by-layer growth method on the surface of the magnetic carbonized cellulose nanoparticles. The extracted analytes were measured by HPLC after extraction. The influential variables such as: extraction time, sorbent amount, volume of desorption solvent, desorption time, ionic strength and solution pH were studied and optimized. Under the optimum condition, the linear ranges of the method were obtained in the range of 0.2–200.0μgL−1 (chlorpyrifos: 0.5-200.0μgL−1, profenofos: 0.2-100.0 μgL−1 and phosalone:0.5-200.0μgL−1). The obtained correlation coefficients (r2) were between 0.9966 - 0.9990. The limits of detection were also calculated to be between 0.06 - 0.15μgL−1 (chlorpyrifos: 0.15μgL−1, profenofos: 0.06 μgL−1 and phosalone: 0.13μgL−1) .The relative standard deviations, were obtained in the range of 1.1 to 3.4%. The method was successfully used to extract and measure the selected organophosphorus pesticides in several real samples including orange, pear, grape, peaches and agricultural water.

Magnetic Polyeugenol Nanoparticles as a New Sorbent for Solid‐Phase Extraction of Polycyclic Aromatic Hydrocarbons in Environmental Water and Food Samples

AbstractIn this study, the magnetized polyeugenol was applied as an efficient adsorbent for pre‐concentration of five target polycyclic aromatic hydrocarbons (PAHs), acenaphthene, fullerene, phenanthrene, fluoranthene and pyrene, in the aqueous samples. Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, thermo‐gravimetric and zeta‐potential analyses, and vibration sample magnetometry were utilized for characterization of the prepared nanocomposite. Key parameters in the extraction efficiency of PAHs including pH, salt content, adsorbent amount, extraction time and volume of desorption solvent were optimized. Under the optimal conditions, a linear response was observed in the concentration range of 1–75 μg L−1 (R2=0.9980–0.9994). The reasonable relative standard deviations (RSDs) from 3.46 to 5.74 (n=3) were also obtained. The enrichment coefficients were calculated to be 17 as the minimum and 20 as the maximum. The obtained limits of detection and limit of quantitation were respectively in range of 0.09–0.19 μg L−1 and 0.32–0.56 μg L−1. Finally, the adsorbent was used to measure the PAHs content of real samples including tap water, river water and brewed tea. The recoveries were between 80.0 %–100.4 % (for tap water) and 91.1 %–100.5 % (for river water) and 83.4 %–102.1 % (for tea sample).

Development of the thin film solid phase microextraction (TF-SPME) method for metabolomics profiling of steroidal hormones from urine samples using LC-QTOF/MS.

In the present study, the development and optimization of a thin film solid phase microextraction method (TF-SPME) was conducted for metabolomics profiling of eight steroid compounds (androsterone, dihydrotestosterone, dihydroepiandrosterone, estradiol, hydroxyprogesterone, pregnenolone, progesterone and testosterone) from urine samples. For optimization of extraction method, two extraction sorbents (PAN-C18 and PS-DVB) were used as they are known to be effective for isolation of low-polarity analytes. The stages of sample extraction and analyte desorption were considered as the most crucial steps in the process. Regarding the selection of the most suitable desorption solution, six different mixtures were analyzed. As a result, the mixture of ACN: MeOH (1:1, v/v) was chosen in terms of the highest analytes' abundances that were achieved using the chosen solvent. Besides other factors were examined such as the volume of desorption solvent and the time of both extraction and desorption processes. The analytical determination was carried out using the ultra-high performance liquid chromatography coupled with high resolution tandem mass spectrometry detection in electrospray ionization and positive polarity in a scan mode (UHPLC-ESI-QTOF/MS). The developed and optimized TF-SPME method was validated in terms of such parameters as extraction efficiency, recovery as well as matrix effect. As a result, the extraction efficiency and recovery were in a range from 79.3% to 99.2% and from 88.8% to 111.8%, respectively. Matrix effect, calculated as coefficient of variation was less than 15% and was in a range from 1.4% to 11.1%. The values of both validation parameters (recovery and matrix effect) were acceptable in terms of EMA criteria. The proposed TF-SPME method was used successfully for isolation of steroids hormones from pooled urine samples before and after enzymatic hydrolysis of analytes.

Transition metal composites for selective analysis of vitamin B2 in rice by ultrahigh-performance liquid chromatography-tandem mass spectrometry

A novel amino-functionalized zinc ferrite nanoparticles/MXene (ZnFe2O4–NH2/MXene composite which consist of ZnFe2O4–NH2 and single/few layers MXene was designed and synthesized as an efficient extractant for analysis of vitamin B2 in rice first combined with ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). As a result, the single/few layer MXene was tightly attached to the spherical ZnFe2O4–NH2 nanoparticles by electrostatic self-assembly interaction, which present large specific surface area and fast mass transfer rate. The relevant experimental parameters, including the pH of the solution, extraction time, adsorbent amount, desorption solvent, desorption solvent volume and desorption time were investigated and optimized. Under optimum conditions, the ZnFe2O4–NH2/MXene composite exhibited excellent selectivity and adsorption capacity for vitamin B2 through hydrogen bonding interactions and the metal-π complexation interaction. The adsorption kinetics, isotherms, and thermodynamic studies were systemically investigated to evaluate the adsorption mechanism and characteristics, which ascribed to chemical adsorption, monolayer adsorption and a spontaneous endothermic process. Furthermore, the performance of the proved method was validated with the good linear correlation coefficient (r = 0.999), low limit of detection (0.86 ng·mL−1) and the limit of quantification (2.98 ng·mL−1), satisfactory recoveries (81.7–102.5%) and reasonable accuracy (RSD<7.8%). The theoretical and technological underpinning for investigating the kinship amongst vitamin alterations and the degree of rice storage was set using this suggested approach to assess vitamin B2 in rice from various years.

Development of paper-immobilized molecularly imprinted polymers by laser pointer activation for methamphetamine extraction with analysis by ion mobility spectrometry

A fast, simple, cheap, and versatile strategy has been proposed for the synthesis of paper-immobilized molecularly imprinted polymers (MIPs) by photoactivated bulk polymerization over a piece of nitrocellulose using a 405 nm laser pointer. Polymerization was carried out using a mixture of methacrylic acid and ethylene glycol dimethacrylate, using methamphetamine as template molecule and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as radical initiator. After investigation of different polymerization parameters, the following experimental conditions were found to give best results: size of nitrocellulose strip (13.5 × 4.0 × 0.8 mm), type of porogen (acetonitrile), polymerization mixture volume (75 µL), and irradiation times (10 min). Experimental conditions (such as sample pH, extraction and desorption time, and type and volume of desorption solvent) were also adjusted for the extraction of methamphetamine using the proposed paper-MIP. Methamphetamine determination was carried out by ion mobility spectrometry providing a limit of detection of 14 µg L−1 and quantitative recoveries from 81 to 95% using spiked urine and oral fluid samples. The proposed paper-immobilized MIP device allows a simple and selective sample extraction procedure for the determination of methamphetamine in oral fluids and urine with a high portability, minimal solvent consumption, and reduced costs compared to other conventional approaches.

Room temperature fabrication of magnetic covalent organic frameworks for efficient enrichment of parabens in water

A novel 4 + 2 covalent magnetic organic framework (COF) with core-shell structure was synthesized for the first time with N, N, N', N'-Tetrakis (4-aminophenyl)-1, 4- benzenediamine (TPDA) and 2, 6-Pyridinedicarboxaldehyde (PCBA) at room temperature. The synthesized magnetic TPDA-PCBA-COF has a large specific surface area and superparamagnetism, which makes it an ideal sorbent for trace analytes enrichment. To this end, we combined it with magnetic solid phase extraction (MSPE) to enrich trace parabens in environmental water. The parameters affecting the enrichment efficiency of magnetic solid phase extraction, such as the amount of Fe3O4@TPDA-PCBA-COF, extraction time, pH of samples, salt concentration, desorption solvent volume and desorption time, were optimized. A simple method for extraction and determination of parabens in water samples by MSPE combined with high performance liquid chromatography (HPLC) was established under optimized conditions. The validation results revealed that the linear ranges were at 1.0–5.0 × 102 ng mL−1 with R value between 0.9915 and 0.9999, the spiked recoveries were in the range of 82.8% to 99.9% and RSDs were lower than 10%. The method was further applied to the determination of parabens in water samples, with recoveries in the range of 82.2% to 110.0% and RSDs ≤ 7.7%. These results suggest that the magnetic TPDA-PCBA-COF could be used as a promising adsorbent for efficient extraction and quantitation of parabens in environmental water samples.

Development of dispersive micro solid phase extraction method based on using Fe3O4@UiO-66-NH2@MIP nanocomposite as an efficient and selective sorbent for the extraction of imidacloprid from fruit juice samples

In this study, a magnetic molecularly imprinted polymer (Fe3O4@UiO-66-NH2@MIP) nanocomposite was synthesized for preconcentration, extraction, and selective analysis of imidacloprid using unique characteristics of magnetic iron oxide nanoparticles, metal–organic framework, and molecular imprinted polymer. The synthesized sorbent was investigated using Scanning electron microscopy and Fourier-transform infrared spectroscopy. The results of the characterization analyses ensured the successful synthesis. The relevant optimization parameters such as amount of the sorbent, type and time of agitation, pH, ionic strength, and type and volume of desorption solvent were investigated and optimized. High performance liquid chromatography-tandem mass spectrometry was used in the analysis of the enriched analytes. Under the optimum conditions detection and quantification limits were 0.187 and 0.625 ng/L, respectively. The linear range of 0.625–80 ng/L with a coefficient of determination of 0.9984 was obtained. The obtained results showed that the synthesized sorbent had excellent selectivity for the analyte, good adsorption capacity, high extraction recovery (92.4 %), acceptable stability, and good reusability. Finally, the developed method was successfully applied for the analysis of imidacloprid in different fruit juice samples.

Determination of fumonisins in edible vegetable oil by MIL-101(Cr) based dispersive solid-phase extraction combined with high-performance liquid chromatography-tandem mass spectrometry

A method was first developed based on MIL-101(Cr) dispersive solid-phase extraction for determining fumonisins in edible vegetable oil. Fumonisins contain hydroxyl and carboxyl groups and were easily adsorbed by MIL-101(Cr) with intermolecular force. With the matrix matching the external standard method for quantification, several extraction factors such as extraction solvent, adsorption dose, extraction time, desorption solvent, desorption solvent volume, desorption time, and filter membrane were optimized. The linear ranges were 5.0–40 μg/L, and the correlation coefficients (r) were greater than 0.9997. The LODs and LOQs of the target analyte were 1.5 and 5.0 μg/kg. At the four spiked concentrations (5, 10, 20, and 40 μg/kg), the recovery rates were between 94.5% and 101.7%, and the RSDs were between 2.02% and 5.32%. The inter-day and intra-day tests recoveries were 98.5%− 99.9% and 93.7%− 98.7%, respectively. The precision of the inter-day and intra-day analysis was 5.09–6.05% and 2.56%− 3.19%, respectively. The pretreatment time of this method is only 1 h, and the efficiency is 4–8 times higher than that of other methods.These results showed that the method was fast, selective, low cost, and sensitive and had obvious advantages for accurately determining and analyzing fumonisins in edible oil samples.

Preparation and application of bimetallic coordination cluster Cu7Mn2 for dispersive solid phase extraction of polycyclic aromatic hydrocarbons in lettuce

In this study, bimetallic coordination cluster Cu7Mn2 was synthesized by solvent thermal method and based on the features of large specific surface area, rich adsorption sites, the material was applied for the dispersive solid-phase extraction of pyrene, fluoranthene, phenanthrene and fluorene in lettuce followed by high performance liquid chromatography analysis. The sythesized Cu7Mn2 cluster was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, hydrophobicity and nitrogen adsorption-desorption experiments. The adsorption kinetics and adsorption isotherms were carrued out. Then, the adsorption mechanism was speculated to be the coexistence of π − π stacking, hydrophobic interaction and N−H···π interaction. The adsorption experimental results indicated that Cu7Mn2 cluster had better adsorption properties for pyrene, fluoranthene, phenanthrene, fluorene than Cu cluster and Mn cluster. The extraction conditions such as the kind and volume of desorption solvent, the adsorption and desorption time, the sample volume and salinity were investigated. Under the optimal conditions, a DSPE-HPLC method was developed for the determination of pyrene, fluoranthene, phenanthrene and fluorene in lettuce. The linearities were 0.5 − 1000 μg/kg for phenanthrene, fluorene and 3−1000 μg/kg for pyrene, fluoranthene (R2 >0.99), respectively. The limits of detection (LODs, S/N = 3) and the limits of quantification (LOQs, S/N = 10) were in the ranges of 0.12−0.81 μg/kg and 0.40 − 2.7 μg/kg, respectively. The intra- and inter-day precisions (RSDs) were less than 2.9% and 4.0%, respectively, and the recoveries were in the range of 94.9% − 101.1%. The established DSPE-HPLC method has been proven to be accurate for the analysis of four polycyclic aromatic hydrocarbons in lettuce samples.

Preparation of an efficient magnetic nano-sorbent based on modified cellulose and carboxylated carbon nano-tubes for extraction of pesticides from food and agricultural water samples before GC-FID analysis

This paper reports the direct synthesis approach of carboxamide functionalized magnetic nano-composite named Fe3O4@SiO2-NH2@dialdehyde cellulose (DAC)@CNT-COOH as an effectual sorbent for the co-extraction of seven agricultural insecticides and herbicides from vegetable, fruit, and water samples using the magnetic dispersive micro-solid-phase extraction procedure. Under the optimized extraction conditions (sorbent amount: 18.1 mg; desorption time: 6.5 min; desorption solvent volume: 185 μL; desorption solvent: acetonitrile; extraction time: 9.5 min; pH of sample solution: 7.0, and salt content: 5.0 % w/v sodium chloride), good linearity within the range 0.5–1200 ng/mL (R2 ≥ 0.998) was achieved. Extraction efficiencies were in the range 63.4–84.1 %, the limits of detection were 0.08–1.0 ng/mL, and acceptable relative recoveries (87.6–103.8 %), and precisions were also achieved (RSDs < 6.8 %, n = 3). Ultimately, the obtained results showed that the developed method could be applied to determine trace amounts of desired analytes in various agricultural water and food samples.

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 tothe 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 0.07μg L-1 for diazinon and chlorpyrifos, respectively. This method showed wide linearity in the range 0.10-1000μg L-1 for diazinon and 0.25-1000μg 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%.

Carbonized metal-organic framework-74/carbon aerogel composites for the efficient extraction of triazole fungicides from fruits and vegetables

To improve the extraction efficiency, availability, and stability of metal-organic framework (MOF) for pipette-tip solid-phase extraction (PT-SPE), a carbonized MOF-74/carbon aerogel composite (CMOF-74/CA) was developed. A carbon aerogel with a surface area of 547.7 m2 g−1 was prepared by carbonizing a watermelon peel. After that, via a hydrothermal reaction, the MOF-74 was in situ grown on the surface. After the pyrolysis at 700 °C for 2 h, the CMOF-74/CA composite was obtained. Through regulating the concentration of reactants, a series of MOF-74/CA and CMOF-74/CA materials were prepared. These materials were used to extract hexaconazole and diniconazole in fruits and vegetables before gas chromatography-flame ionization detection (GC-FID). The adsorbent type and amount, sample pH, and the desorption solvent type and volume were optimized factor by factor. Under the optimized conditions, a PT-SPE-GC-FID method was established. Moreover, good linearity in the concentration ranges of 0.098–200.0 mg kg−1 and 0.196–200.0 mg kg−1, and detection limits ranging between 0.033 and 0.065 mg kg−1 were achieved for two triazole fungicides (TFs). The relative standard deviations (n = 3) for intra-day and inter-day tests were in the ranges of 3.1–3.2% and 3.0–3.4%, respectively. The method showed satisfactory analytical performance in different samples with good relative recoveries in the range of 72.6–116%. Compared with some methods, it displayed wider linearity, better or comparable sensitivity, and enhanced analytical precision.