Magnetic multi-walled carbon nanotubes assisted dispersive solid phase extraction of nerve agents and their markers from muddy water

A novel automated multi-cycle magnetic solid-phase extraction coupled to LC-MS/MS to study the disorders of six functional B vitamins in patients with gastroenterology and hyperhomocysteinemia

B vitamins are essential for human life and their disorders can cause a variety of diseases. Solid-phase extraction (SPE) coupled to LC-MS/MS is a preferred technique for determining multiple B vitamins, however, their complexity in real biological matrices makes it hard to achieve satisfactory recovery and accuracy when simultaneous detection. In this study, a novel automated multi-cycle magnetic SPE (MSPE) coupled to the LC-MS/MS method was established using a mixed-mode anion exchange magnetic adsorbent for the simultaneous extraction of six functional B vitamins, including methylmalonic acid, riboflavin, pantothenic acid, 4-pyridoxic acid, folic acid, and 5-methyltetrahydrofolate. After three consecutive MSPE cycles, the recoveries of all analytes were between 51.5% and 89.6%. The method exhibited excellent sensitivity and linearity, with a dynamic range of 200-fold (R > 0.99 for all analytes), exceptional accuracy (ranging between 95.4% and 105.6%) and precision (with RSDs ≤ 6.2%) without significant matrix effects or interferences. Compared to manual SPE method, the automated multi-cycle MSPE method has better feasibility and greater vitamin coverage. It shows a high correlation with the manual method for the detection of 5-methyltetrahydrofolate and folate (R > 0.99). A study of patients from the gastroenterology department showed that those undergoing surgery and those with malignancies may be at risk of folate deficiency. In addition, patients with hyperhomocystinemia had higher levels of methylmalonic acid and lower levels of 5-methyltetrahydrofolate, which correlated with homocysteine levels (R = 0.404 and -0.311, respectively) and showed dose-response relationships. This method is highly automated and cost-effective, with minimal systematic error, making it suitable for the analysis of clinical samples.

Magnetic activated carbon as an adsorbent for extraction of DMMP from aqueous samples followed by GC-IMS analysis

Micro-porous magnetic activated carbon was prepared under ultrasonic irradiation as an adsorbent for dispersed solid phase extraction of dimethyl methyl phosphonate from water samples, before analysis by gas chromatography-ion mobility spectrometry. The magnetic activated carbon was synthesized and characterized by using a vibrating sample magnetometer, Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction techniques. Then, the effects of the amount of sorbent, extraction time and pH of the sample in the dispersive solid phase extraction method were investigated and optimized by the response surface method. The dispersion of 20 mg adsorbent powder in a 50 mL water sample for 5 minutes with chloroform as the desorption solvent showed an average recovery value of 95% for dimethyl methyl phosphonate. Afterward, the method was used successfully for the determination of dimethyl methyl phosphonate in river and spring water. The linear range was obtained to be 0.05-1 μg mL-1. The limit of detection and the limit of quantification were obtained to be 0.02 μg mL-1 and 0.05 μg mL-1 respectively. The analysis also showed good reproducibility with a relative standard deviation value of 3.1%. This method was shown to be easy, fast, reliable, and inexpensive.

Nature-based approaches to reducing the environmental risk of organic contaminants resulting from military activities

As is the case with many other industrial activities, the organic contaminants at military-impacted sites may pose significant hazards to the environment and human health. Given the expected increase in defense investments globally, there is a need to make society aware of the risks of emissions of organic contaminants generated by military activities and to advance risk minimization approaches. The most recent advances in environmental analytical chemistry, persistence, bioavailability and risk assessment of organic contaminants indicate that efficient risk reductions through biological means are possible. This review debates the organic contaminants of interest associated with military activities, the methodology used to extract and analyze these contaminants, and the nature-based remediation technologies available to recover these sites. In addition, we revise the military environmental regulatory frameworks designed to sustain such actions. Military activities that potentially release organic contaminants on land could be classified as infrastructure and base operations, training exercises and armed conflicts; additionally, chemicals may include potentially toxic compounds, energetic compounds, chemical warfare agents and military chemical compounds. Fuel components, PFASs, TNT, RDX and dyphenylcyanoarsine are examples of organic contaminants of environmental concern. Particularly in the case of potentially toxic and energetic compounds, bioremediation and phytoremediation are considered eco-friendly and low-cost technologies that can be used to remediate these contaminated sites. In addition, this article identifies implementing the bioavailability of organic contaminants as a justifiable approach to facilitate the application of these nature-based approaches and to reduce remediation costs. More realistic risk assessment in combination with new and economically feasible remediation methods that reduce risk by reducing bioavailability (instead of lowering the total contaminant concentration) will serve as an incentive for the military and regulators to accept nature-based approaches.

Simple Synthesis of Fe3O4@-Activated Carbon from Wastepaper for Dispersive Magnetic Solid-Phase Extraction of Non-Steroidal Anti-Inflammatory Drugs and Their UHPLC–PDA Determination in Human Plasma

In the present society, the recycling and reuse of valuable substances are of utmost importance for economic and environmental purposes. At the same time, there is a pressing need to develop new methods to protect the ecosystem from many human activities, including those that have contributed to an ever-increasing presence of pharmaceutical pollutants. In this study, a straightforward approach that applies a magnetic carbon composite for the effective removal of NSAIDs from biological fluids is reported. The composite was produced by recycling wasted handkerchiefs, to provide cellulose to the reactive system and then transformed into carbon via calcination at high temperature. The morphological and structural features of the prepared “Fe3O4@-activated carbon” samples were investigated via thermal analysis, X-ray diffraction, Raman spectroscopy, and scanning electron microscopy. Magnetic solid-state extraction was carried out to reveal the adsorption capabilities of the magnetic carbon composite and then combined with UHPLC–PDA for the determination and quantification of five NSAIDs (furprofen, indoprofen, ketoprofen, flurbiprofen, and indomethacin). The method developed herein proved to be fast and accurate. The adsorbent could be reused for up to 10 cycles, without any decrease in performance; thus, it contributes to an intelligent and sustainable economic strategy projected toward minimal waste generation.

Magnetic Polydopamine Modified with Choline-Based Deep Eutectic Solvent for the Magnetic Solid-Phase Extraction of Sulfonylurea Herbicides in Water Samples

A novel magnetic solid-phase extraction technique coupled to ultraperformance liquid chromatography has been developed for separation and preconcentration of four sulfonylurea herbicides (sulfosulfuron, bensulfuron-methyl, pyrazosulfuron-ethyl and halosulfuro-methyl) in aqueous samples. The key point of this method was the application of a novel magnetic nanomaterial that composed of a low eutectic solvent as a shell coated on the magnetic core modified by polydopamine. The extensive active sites outside the low eutectic solvent can effectively adsorb the target herbicide in the extraction process. The obtained magnetic adsorbent was characterized with fourier transform infrared spectrometry, scanning electron microscopy and vibrating sample magnetometer. The influence parameters relevant to this method were optimized. Under the optimum conditions, good linearities could be obtained within the range of 1.0-200 μg L-1 for all analytes, with correlation coefficients ≥0.9908. The limit of detections of the method was between 0.0074 and 0.0100 μg L-1 and the relative standard deviations were 1.1-3.6%. The enrichment factor is 66.6. In the final experiment, the proposed method was successfully applied to the analysis of sulfonylurea herbicides residue in environment and drinking-water samples, and the obtained recoveries were between 70.6% and 109.4%.

Magnetic solid-phase extraction based on magnetic amino modified multiwalled carbon nanotubes for the fast determination of seven pesticide residues in water samples

A rapid and simple analytical method based on magnetic solid-phase extraction with magnetic amino modified multiwalled carbon nanotubes with ultra-high performance liquid chromatography-tandem mass spectrometry is reported for the determination of seven pesticides (futriafol, metalaxyl, myclobutanil, napropamide, epoxiconazole, fipronil and diniconazole) in water samples. In this study, magnetic amino modified multi-walled carbon nanotubes were synthesized and selected as a new kind of material to adsorb pesticides in the water samples. Various magnetic solid-phase extraction parameters, such as the amount and type of adsorbent, extraction methods, extraction time, the type and volume of desorption solvent, desorption time and solution ionic strength, were systematically optimized. Under optimum conditions, the method validation results showed good linearity and recoveries. The calibration curves were in the range of 1.0-100 ng mL-1 for napropamide, epoxiconazole, metalaxyl, and fipronil, while they were 5.0-500 ng mL-1 for futriafol, myclobutanil, and diniconazole, with determination coefficients (R2) higher than 0.9909. The limits of quantification were 1.0-5.0 ng mL-1 and the limits of detection were 0.3-1.5 ng mL-1. The recoveries of the seven pesticides ranged from 80.4% to 103.2%. This developed method, which is more convenient and effective in comparison with traditional methods, has been successfully applied for the analysis of pesticides in water samples qualitatively and quantitatively.

Sampling and analyses of surfaces contaminated with chemical warfare agents by using a newly developed triple layered composite wipe

A three-layered composite wipe was fabricated by laminating individual layers of non-woven polypropylene, activated carbon fabric (ACF) and aramid fabric for the sampling and investigation of chemical warfare agents (CWA)-contaminated urban porous and non-porous surfaces. The material of main ACF layer was characterized to ascertain its suitability to act as an efficient adsorbent for the surface wipe sampling. The performance of ACF-based composite wipe was determined by evaluating its extraction efficiency, wiping efficacy and adsorption capacity for the sampling of blister and nerve agent class of CWA-contaminated surfaces using gas chromatography-mass spectrometry (GC-MS). Parameters like amount of wipe required, solvent selection, amount of solvent, time of extraction etc. were optimized to achieve the maximum recovery of contaminating analytes required for the forensic investigations. Overall recoveries of contaminating analytes after sampling and extraction were found to be in the range of 45-85% for all types of surfaces. No breakthrough in wiping process was noticed up to contamination density (CD) 1.6 mg/cm² for non-porous surface and 3.2 mg/cm² for porous surfaces. ACF-based wipe was found capable to significantly reduce the vapour hazards from liquid sulphur mustard (HD) and sarin (GB). Contamination from surfaces could be preserved within the wipe up to 15 days for the extended forensic investigation purposes. Limit of detections (LOD) of contaminants was determined in the range of 0.8-6.8 ng/cm² while limit of quantitation (LOQ) was achieved up to the range of 2.4-14.4 ng/cm² for wipe sampling of different surfaces. Graphical abstract.

Magnetic nanostructures for preconcentration, speciation and determination of chromium ions: A review

Magnetic nanoparticles based solid-phase extraction is a new analytical technique based on the use of magnetic sorbents for the preconcentration and quantification of different inorganic and organic species. The present review concentrates on recent developments that have been built in magnetic nanostructures-based solid phase extraction, speciation and quantification of chromium ions. Besides, a description of the preparation, characterization as well as applications of various types of magnetic nanostructures, either with an inorganic or organic coating of the magnetic core, is presented. In addition, the most important analytical characteristics such as preconcentration factor, linear range, and limits of detection were carefully reported and compared. On the other hand, the removal of the chromium ions by magnetic solid phase extraction was not discussed in the review.

Polydopamine-assisted attachment of β-cyclodextrin onto iron oxide/silica core-shell nanoparticles for magnetic dispersive solid phase extraction of aromatic molecules from environmental water samples

Pollution monitoring in a contaminated environmental water samples is a big challenge. In this article, immobilization of β-cyclodextrin molecules onto the magnetic core-shell silica nanoparticles was conducted by using adhesive properties of polydopamine. The synthesis path was included of three steps: producing Fe₃O₄ nanoparticles as a core, coating the cores with a silica layer, and further coating with β-cyclodextrin molecules. The structural characteristics of the synthesized nanocomposite were investigated by using attenuated total reflection-Fourier transform infrared spectroscopy, x-ray diffraction analysis, field emission scanning microscopy, transmission electron microscopy, dynamic light scattering, vibrating-sample magnetometer and energy-dispersive X-ray spectroscopy. Afterwards, obtained nanocomposite was used to extract eight polycyclic aromatic hydrocarbons from environmental water samples. Results were demonstrated that analyts with different chemical structures had different extraction manners during the process. Important effective parameters on the extraction efficiency; such as sorbent type and mass, desorption solvent (type and volume), salt concentration and the time of extraction & desorption; were investigated. Under the optimum operating conditions, good linearity within the range of 1-1000 ng/mL was obtained while coefficient of determination (r²) was in the range of 0.990-0.998. The limits of detection were between 0.04 and 0.57 ng/mL, and the enrichment factor was found to be 21-90. This nanocomposite was also applied for the extraction and enrichment of aromatic analytes from the canal and rain water samples prior to gas chromatography analysis.

Development of magnetic carbon nanotubes for dispersive micro solid phase extraction of the cyanide metabolite, 2-aminothiazoline-4-carboxylic acid, in biological samples

2-aminothiazoline-4-carboxylic acid (ATCA) is a minor metabolite of cyanide and is suggested to be a promising biomarker for cyanide exposure due to its specificity to cyanide metabolism and its excellent short- and long-term stability during storage. In this study, magnetic carbon nanotubes, including magnetic multi-walled carbon nanotubes (Mag-MWCNT) and magnetic single-walled carbon nanotubes (Mag-SWCNT) were synthesized as a novel sorbent for dispersive micro solid phase extraction (d-μSPE) to extract ATCA from biological matrices. ATCA spiked deionized water samples with the addition of the isotopic internal standard (ATCA - ¹³C, ¹⁵N) were subjected to Mag-CNT/d-μSPE to confirm extraction efficiency of this new technique. The extracted ATCA was derivatized and quantitated using gas chromatography/mass spectrometry (GC/MS) analysis. The extraction parameters were optimized and a detection limits of 15 and 25 ng/mL were obtained for synthetic urine and bovine blood respectively with a linear dynamic range of 30-1000 ng/mL. The optimized Mag-CNT/d-μSPE method facilitated efficient extraction of ATCA using 2 mg of Mag-MWCNT with a 10-minute extraction time. The current assay was also found to be effective for the extraction of ATCA with average recoveries of 97.7 ± 4.0% (n = 9) and 96.5 ± 12.1% (n = 9) from synthetic urine and bovine blood respectively. The approach of using Mag-CNT to facilitate d-μSPE offered a novel alternative to extract ATCA from complex biological matrices.

PdII Immobilized on Ferromagnetic Multi-Walled Carbon Nanotubes Functionalized by Aminated 2-Chloroethylphosphonic Acid with S-Methylisothiourea (FMMWCNTs@CPA@SMTU@PdII NPs) Applied as a Highly Efficient and Recyclable Nanostructured Catalyst for Suzuki–Miyaura and Mizoroki–Heck Cross-Coupling Reactions in Solvent-Free Conditions

The new ferromagnetic nanostructured FMMWCNTs@CPA@SMTU@PdII NPs (IV) as an eco-friendly heterogeneous nanocatalyst with a particle size of ~20–30nm reported earlier by our group has been found to be very effective for Suzuki–Miyaura and Mizoroki–Heck cross-coupling reactions at ambient temperature. The procedure has been applied for a wide range of aryl halides, arylboronic acids, and alkenes. The magnetic separation by an external magnetic field, mild reaction conditions, and catalyst reusability up to four times without significant decrease in catalytic activity (reduced catalytic activity from 11 to 18% in the fifth, sixth, and seventh cycles) made the present method sustainable and economically viable for C–C cross-coupling reactions.

Green construction of Fe3O4@GC submicrocubes for highly sensitive magnetic dispersive solid-phase extraction of five phthalate esters in beverages and plastic bottles

A well-designed core-shelled Fe₃O₄@graphitic carbon (Fe₃O₄@GC) submicrocube was in situ constructed in a simple, relatively green and eco-friendly ways basing on one-step pyrolysis of low-cost waste napkins-coated Fe₂O₃ submicrocubes. The Fe₃O₄@GC submicrocubes showed unique architectures where in situ generated thin graphitic carbon layer wrapped on the surface of Fe₃O₄, resulting in excellent affinity to five phthalate esters (PAEs), good reusability and rapid magnetic separation, therefore were employed as magnetic dispersive solid-phase extraction material combined with HPLC to simultaneously detect five trace PAEs in beverages and plastic bottles. Under optimized conditions, recoveries (80.0%-112.8%), precision (RSDs ≤ 8.8%), and limits of detection (LODs) for beverages (0.09-0.28 μg L^-1) and plastic bottles (0.01-0.03 μg g^-1) were obtained. This work not only establishes an effective method for simultaneous determination of five PAEs, but also opens up a new strategy to design/construct magnetic graphitic carbon-encapsulated core-shell materials using low-cost/recyclable napkins as carbon source.

Cu- and S- @SnO2 nanoparticles loaded on activated carbon for efficient ultrasound assisted dispersive µSPE-spectrophotometric detection of quercetin in Nasturtium officinale extract and fruit juice samples: CCD-RSM design

A simple, rapid, and efficient method of dispersive micro solid phase extraction (D-μ-SPE) combined with UV-Vis spectrophotometry via ultrasound-assisted (UA) was applied for the determination and preconcentration of quercetin in extract of watercress (Nasturtium officinale), fruit juice and water samples. The sorbent in this method was synthesized by doping copper and sulfide into the tetragonal structure of SnO₂-nanoparticles (Cu- and S- @SnO₂-NPs) and subsequently loading it on activated carbon (AC). The D-μ-SPE parameters with direct effect on the extraction efficiency of the targeted analyte, such as sample pH, volume of eluent, sorbent mass and ultrasound time were optimized using central composite design method. Under optimized conditions, the calibration graph for quercetin was linear in the range of 20-4000 ng mL^-1; the limit of detection and quantitation were 4.35 and 14.97 ng mL^-1, respectively and the enrichment factor was 95.24. Application of this method to analyze spiked extract, fruit juice and water samples resulted in acceptable recovery values ranging from 90.3% to 97.28% with intra-day and inter-day relative standard deviation values lower than 6.0% in all cases. Among the equilibrium isotherms tested, Langmuir was found to be the best fitted model with maximum sorption capacity of 39.37 mg g^-1, suggesting a homogeneous mode of sorption for quercetin.

A magnetic cellulose-based carbon fiber hybrid as a dispersive solid-phase extraction material for the simultaneous detection of six bisphenol analogs from environmental samples

A hollow porous NiMn2O4 nanosphere-decorated cellulose-based carbon fiber (CCF, using recyclable cotton wool as the carbon fiber source) hybrid was fabricated via a relatively green and eco-friendly hydrothermal synthetic route, followed by calcination treatment. The in situ growth of hollow porous NiMn2O4 on the CCFs led to it being decorated over the CCF surface uniformly. The NiMn2O4/CCFs hybrid displayed excellent extraction capabilities and magnetic reusability. Benefiting from its high porosity, large specific surface area, and superior chemical affinities to bisphenol analogs (BPs), and the synergistic effect between NiMn2O4 and CCFs, NiMn2O4/CCFs as an adsorbent was applied to the extraction of low concentrations of BP compounds, displaying excellent extraction capabilities. A magnetic dispersive solid phase extraction (MDSPE) method combined with HPLC was developed for detecting six BPs in real environmental samples. Under optimal conditions, the detection limits and recoveries were 0.56-0.83 ng mL-1 and 84.3-103.5% (RSD ≤ 4.5%). It was confirmed that NiMn2O4/CCFs was a type of rapid and high efficiency MDSPE material for the analysis of multiple BP compounds in environmental samples.

Multi-residue enantiomeric analysis of 18 chiral pesticides in water, soil and river sediment using magnetic solid-phase extraction based on amino modified multiwalled carbon nanotubes and chiral liquid chromatography coupled with tandem mass spectrometry

This manuscript describes, for the first time, the multi-residue analysis of 18 chiral pesticides at enantiomeric levels in both environmental liquid (river water, influent and effluent wastewater) and solid matrices (agricultural soil, forestal soil and river sediment) based on magnetic solid-phase extraction (MSPE) and chiral liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Magnetic amino modified multiwalled carbon nanotubes (m-MWCNTs-NH₂) were prepared and firstly applied to adsorb pesticides from complex matrices. Response surface methodology (RSM) was applied to assist the multivariable optimization. The simultaneous enantioseparation of the chiral pesticides was performed on a Chiralpak IG column. Under the optimum conditions, the mean recoveries for pesticides enantiomers from the water matrices ranged from 81.1 to 106.3% with intra-day RSD of 2.1-11.9% and inter-day RSD of 2.6-12.7%; the mean recoveries for all enantiomers from the solid matrices ranged from 80.3 to 105.9% with intra-day RSD of 2.3-10.9% and inter-day RSD of 4.0-13.4%. Good linearity was achieved for all enantiomers with determination coefficients (r²) greater than 0.9912. Method quantification limits were below 2.04ng L^-1 in liquid matrices and below 0.50ng g^-1 in solid matrices. The developed method offered some advantages, such as simple operation, rapidity and high concentration factor. Therefore, it is suitable for monitoring the enantiomeric compositions of chiral pesticides in different environmental matrices.

Polypyrrole-modified magnetic multi-walled carbon nanotube-based magnetic solid-phase extraction combined with dispersive liquid–liquid microextraction followed by UHPLC-MS/MS for the analysis of sulfonamides in environmental water samples

Polypyrrole modified magnetic multi-walled carbon nanotubes were prepared and applied as an efficient adsorbent for magnetic solid-phase extraction.

Green and facile approach for enhancing the inherent magnetic properties of carbon nanotubes for water treatment applications

Current methods for preparing magnetic composites with carbon nanotubes (MCNT) commonly include extensive use of treatment with strong acids and result in massive losses of carbon nanotubes (CNTs). In this study we explore the potential of taking advantage of the inherent magnetic properties associated with the metal (alloy or oxide) incorporated in CNTs during their production. The as-received CNTs are refined by applying a permanent magnet to a suspension of CNTs to separate the high-magnetic fraction; the low-magnetic fraction is discarded with the solvent. The collected MCNTs were characterized by a suite of 10 diffraction and spectroscopic techniques. A key discovery is that metallic nano-clusters of Fe and/or Ni located in the interior cavities of the nanotubes give MCNTs their ferromagnetic character. After refinement using our method, the MCNTs show saturation magnetizations up to 10 times that of the as-received materials. In addition, we demonstrate the ability of these MCNTs to repeatedly remove atrazine from water in a cycle of dispersion into a water sample, adsorption of the atrazine onto the MCNTs, collection by magnetic attraction and regeneration by ethanol. The resulting MCNTs show high adsorption capacities (> 40 mg-atrazine/g), high magnetic response, and straightforward regeneration. The method presented here is simpler, faster, and substantially reduces chemical waste relative to current techniques and the resulting MCNTs are promising adsorbents for organic/chemical contaminants in environmental waters.

Polythiophene-Chitosan Magnetic Nanocomposite as a Highly Efficient Medium for Isolation of Fluoxetine from Aqueous and Biological Samples

Polythiophene/chitosan magnetic nanocomposite as an adsorbent of magnetic solid phase extraction was proposed for the isolation of fluoxetine in aqueous and biological samples prior to fluorescence detection at 246 nm. The synthesized nanoparticles, chitosan and polythiophene magnetic nanocomposite, were characterized by scanning electron microscopy, FT-IR, TGA, and EDAX. The separation of the target analyte from the aqueous solution containing the fluoxetine and polythiophene/chitosan magnetic nanocomposite was simply achieved by applying external magnetic field. The main factors affecting the extraction efficiency including desorption conditions, extraction time, ionic strength, and sample solution pH were optimized. The optimum extraction conditions were obtained as 10 min for extraction time, 25 mg for sorbent amount, 50 mL for initial sample volume, methanol as desorption solvent, 1.5 mL for desorption solvent volume, 3 min for desorption time, and being without salt addition. Under the optimum conditions, good linearity was obtained within the range of 15-1000 μg L(-1) for fluoxetine, with correlation coefficients 0.9994. Furthermore, the method was successfully applied to the determination of fluoxetine in urine and human blood plasma samples. Compared with other methods, the current method is characterized with highly easy, fast separation and low detection limits.

Selective dispersive solid phase extraction-chromatography tandem mass spectrometry based on aptamer-functionalized UiO-66-NH2 for determination of polychlorinated biphenyls

In this paper, a novel dispersive solid phase extraction (dSPE) adsorbent based on aptamer-functionalized magnetic metal-organic framework material was developed for selective enrichment of the trace polychlorinated biphenyls (PCBs) from soil sample. Firstly, we developed a simple, versatile synthetic strategy to prepare highly reproducible magnetic amino-functionalized UiO-66 (Fe3O4@PDA@UiO-66-NH2) by using polydopamine (PDA) as covalent linker. Then amino-functionalized aptamers which can recognize 2,3',5,5'-tetrachlorobiphenyl (PCB72), 2',3',4',5,5'-pentachlorobiphenyl (PCB106) were covalent immobilized on UiO-66-NH2 through coupling reagent of glutaraldehyde. Aptamer-functionalized adsorbent (Fe3O4@PDA@UiO-66-Apt) can specifically capture PCBs from complex matrix with high adsorption capacity based on the specific affinity of aptamer towards target. Moreover, the adsorbent can be easily isolated from the solution through magnetic separation after extraction. Afterwards, the detection was carried out with gas chromatography tandem mass spectrometry (GC-MS). The selective dSPE pretreatment coupled with GC-MS possessed high selectivity, good binding capacity, stability, repeatability and reproducibility for the extraction of PCBs. Furthermore, the adsorbent possessed good mechanical stability which can be applied in replicate at least for 60 extraction cycles with recovery over 80%. It provided a linear range of 0.02-400ngmL(-1) with a good correlation coefficient (R(2)=0.9994-0.9996), and the limit of detection was found to be 0.010-0.015ngmL(-1). The method was successfully utilized for the determination of PCBs in soil samples.

Single vial sample preparation of markers of nerve agents by dispersive solid-phase extraction using magnetic strong anion exchange resins

A sample preparation method involving extraction, enrichment and derivatization of acidic degradation products of nerve agents was developed using magnetic strong anion exchange resins (MSAX). The method was performed in a single vial involving magnetic dispersive solid phase extraction (MDSPE). Analytes were derivatized with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) in the presence of resins. MSAX were custom synthesized using Fe3O4 nanoparticles as core, 4-vinylpyridine-co-divinylbenzene as polymer shell and quaternary pyridinium function as anion-exchanger. Hydroxide ions were the counter-anions of MSAX to effectively capture the acidic alkyl alkylphosphonic acids (AAPAs) and alkylphosphonic acids (APAs). Quantitative measurements of analytes were performed in the selected ion monitoring mode of GC-MS. Full scan mode of analysis was followed for identifications. Under the optimized conditions analytes were recovered in the range of 39.7-98.8% (n=3, relative standard deviations (RSD) from 0.3 to 6.5%). Limits of detection (LODs) were in the range of 0.1-1.1ngmL(-1); and the linear dynamic range was 5-1000ngmL(-1) with r(2) of 0.9977-0.9769. Applicability of the method was tested with rain-, tap-, muddy-water and Organization for Prohibition of Chemical Weapons (OPCW) Proficiency Test samples.