Sorbent For Magnetic Solid-phase Extraction Research Articles

Core-shell magnetic covalent organic polymer nanocomposites as an adsorbent for the extraction of flavonoids.

A novel 3D magnetic nanocompositematerialbased on covalent organic polymers was successfully synthesized and utilized as an efficient sorbent for magnetic solid-phase extraction. It exhibited a regular core-shell structure, large specific surface area, superior stability, and paramagnetism. To evaluate its extraction efficiency, six flavonoids were tested, demonstrating maximum adsorption capacities ranging from 90 to 218mg/g. Additionally, the material exhibited remarkable reusability and mechanical stability, maintaining its original state over eight cycles with consistent recovery. An analytical strategy combining magnetic solid-phase extraction with high performance liquid chromatography and tandem mass spectrometry was developed for the determination of flavonoids in orange, honey, soybean, and Dioscorea bulbifera L. samples. The low limits of detection (0.01-0.1ng/mL) and limits ofquantification (0.05-0.5ng/mL), as well as satisfactory recovery (80.4-114.8%), were obtained. The linear range started from the limits of quantification to 500ng/mL with R2 ≥ 0.9929. These results suggest that the prepared adsorbent possesses excellent adsorption capabilities for flavonoids, highlighting its significant potential for detecting these compounds in complex sample matrices.

Fast and efficient extraction and determination of nonsteroidal anti-inflammatory drugs using poly(8-hydroxyquinoline)-coated magnetic graphene oxide nanocomposite prior to capillary electrophoresis analysis in wastewater, breast milk, and urine samples.

In this study, magnetic graphene oxide coated with poly(8-hydroxyquinoline) was successfully synthesized, characterized, and utilized as a novel sorbent for the ultrasonic-assisted dispersive magnetic solid-phase extraction of naproxen and ibuprofen. These analytes served as representative analytes for two nonsteroidal anti-inflammatory drugs in various real samples. Characterization techniques, such as IR, X-ray powder diffraction, field emission scanning electron microscopy, energy-dispersive X-ray-mapping, and Brunauer-Emmett-Teller (BET), were used to confirm the correctness synthesis and preparation of the nanocomposites. Effective parameters on the extraction efficiency were investigated to maximize the analytical performance of the developed method. The dynamic range (1-1000µgL-1), coefficients of determination (R2≥0.997), the limits of detection (0.3-1.0µgL-1), and limit of quantification (1.0-3.0µgL-1), intra-day and inter-day precisions (3.5%-7.2%) were achieved. The method validation results showed extraction recovery ranging from 80.4% to 96.0% and preconcentration factors ranging from 137 to 140.

A fungal hyphae-derived biomass carbon for magnetic solid-phase extraction of the organochlorine pesticides in water samples, tea beverages, and Chinese traditional medicines before gas chromatography-tandem mass spectrometry determination

A magnetic biochar nanomaterial derived from fungal hyphae was introduced into the sample preparation field. The magnetic fungal hyphae-derived biomass carbon (MFHBC) could be produced by a controllable hydrothermal method. In order to obtain the best sorbent for magnetic solid-phase extraction (MSPE), the reaction conditions containing temperature, time and the consumption of fungal hyphae were investigated. A series of MFHBC materials were characterized by vibrating sample magnetometers, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy. A material with a satisfactory saturation magnetization (21.58 emu g-1) and largest surface area (88.06 m2 g-1) was selected as the sorbent to extract ten typical organochlorine pesticides (OCPs). The extraction conditions were optimized as 20 mL of sample solution with 70 mg of sorbent and 2.0 g of NaCl oscillated at 50 °C for 5.0 min. And the optimum desorption was performed by oscillating sorbent in 1.0 mL acetonitrile for 5.0 min. Then, the MFHBC-based MSPE-GC–MS/MS methods were established for different samples including water samples, tea beverages, and Chinese traditional medicines. The linearities were 10–2500 ng L−1 or 100–25,000 ng kg−1, and the limits of detection were 0.3–13.9 ng L−1 for water sample, 0.1–9.7 ng L−1 for tea beverage samples, 0.1–21.4 ng L−1 for Shenqi Fuzheng injection samples, and 7.2–278.3 ng kg−1 for Astragali Radix decoction pieces. Except for satisfactory repeatability (RSDs ≤13.8%) in intra-day and inter-day tests (n = 3), the reproducibility (RSDs ≤13.5%, n = 3) of MFHBC was acceptable. The methods were applied in the determination of OCPs from above real samples, with the recoveries of 80.5–117.2% and the RSDs (n = 3) <8.9%. The methods were suitable in the sensitive determination of OCPs from simple to complex matrix samples.

Quaternary ammonium salt modified magnetic solid-phase extraction beads with different chain lengths for efficient enrichment of five types of folates in blood

This study used quaternary ammonium functionalized magnetic beads (QAMBs) as magnetic solid-phase extraction (MSPE) sorbents and liquid chromatography-tandem mass spectrometry (LC-MS) to analyze five folates in a way that was both effective and sensitive. The developed magnetic beads had high BET surface areas up to 434.4 m2/g and strong positive zeta potentials above 40 mV. The conditions for MSPE were optimized. Under the chosen conditions, the linear ranges of the studied folates were 10–10000 ng/L, and the LODs were found to be 1 ng/L. This method was also successfully applied to analyze human plasma samples, giving satisfactory results (recovery of 86.4–98.8 %) and accomplishing it in a short time (i.e., 5 min). The proposed method would be employed for detecting other acids in blood.

Development of an innovative analytical method for forensic detection of cocaine, antidepressants, and metabolites in postmortem blood using magnetic nanoparticles.

Cocaine and antidepressants rank high globally in substance consumption, emphasizing their impact on public health. The determination of these compounds and related substances in biological samples is crucial for forensic toxicology. This study focused on developing an innovative analytical method for the determination of cocaine, antidepressants, and their related metabolites in postmortem blood samples, using unmodified commercial Fe3O4 nanoparticles as a sorbent for dispersive magnetic solid-phase extraction (m-d-SPE), coupled with liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) analysis. An aliquot of 100 µL of whole blood and 5 µL of the internal standard pool were added to 30mg of nanoparticles. The nanoparticles were separated from the sample using a neodymium magnet inserted into a 3D-printed microtube rack. The liquid was then discarded, followed by desorption with 300 µL of 1/1/1 acetonitrile/methanol/ethyl acetate. The sample was vortexed and separated, and 1.5 µL of the organic supernatant was injected into the LC-MS/MS. The method was acceptably validated and successfully applied to 263 postmortem blood samples. All samples evaluated in this study were positive for at least one substance. The most frequent analyte was benzoylecgonine, followed by cocaine and cocaethylene. The most common antidepressants encountered in the analyzed samples were citalopram and fluoxetine, followed by fluoxetine's metabolite norfluoxetine. This study describes the first report of this sorbent in postmortem blood analysis, demonstrating satisfactory results for linearity, precision, accuracy, and selectivity for all compounds. The method's applicability was confirmed, establishing it as an efficient and sustainable alternative to traditional techniques for forensic casework.

Magnetic phytic acid-modified kapok fiber biochar as a novel sorbent for magnetic solid-phase extraction of antidepressants in biofluids

BackgroundTherapeutic drug monitoring (TDM) of antidepressants is essential for monitoring patient medication to avoid drug toxicity, complications, or nonadherence. Chromatographic techniques with high sensitivity and reproducibility are the main detection method for antidepressants. Effective pretreatment of biological sample processes is necessary prior to instrumental analysis. Magnetic solid-phase extraction (MSPE) has received much attention for its advantages of simple operation, rapidity, cost-effectiveness and low organic solvent consumption. Therefore, the development of a suitable and green magnetic sorbent for the detection of antidepressants in plasma and urine is apparently necessary. (88) ResultsA magnetic phytic acid-modified kapok fiber biochar sorbent (Fe3O4/PAKFBC) was successfully synthesized by pyrolytic impregnation and physical milling methods. Fe3O4/PAKFBC exhibited a large specific surface area (214 m2 g−1) and a rich pore structure (5–10 nm). The extraction equilibrium, using 10 mg Fe3O4/PAKFBC, can be completed in about 1 min. The density functional theory (DFT) results showed that the adsorption mechanism of Fe3O4/PAKFBC on the six antidepressants mainly included electrostatic interactions, van der Waals interactions, π-π interactions and weak hydrogen bonding. Examination using the greenness assessment tools showed that the developed method exhibited excellent greenness. By combining with liquid chromatography-ultraviolet (LC-UV), a quantitative method with good linearity (R2 > 0.993) and relative recoveries (92.4–107.7%) and negligible matrix effect (−11.5–6.0%) was developed. The Fe3O4/PAKFBC successfully detected six antidepressants in plasma and urine samples, requiring no pH adjustment with buffer salts. (142) SignificanceThe environmental sustainability of the proposed methods was affirmed by six greenness evaluation tools, all indicating exceptional eco-friendliness. The Fe3O4/PAKFBC demonstrated outstanding greenness in both its creation and analytical application, proving highly effective in real sample applications and showcasing potential for broader use. This study contributes to a deeper and broader understanding of the microscopic adsorption mechanism, which can help in the optimization and development of more green sorbents. (69).

Dissolution-precipitation method concatenated sodium alginate/MOF-derived magnetic multistage pore carbon magnetic solid phase extraction for determination of antioxidants and ultraviolet stabilizers in polylactic acid food contact plastics

Antioxidants and UV stabilizers have some endocrine disrupting effects and liver toxicity. Both types of additives are still widely used in food contact plastics to improve the durability of plastic products. However, efficient and rapid detection of antioxidants and UV stabilizers has been a challenge due to the complexity of the plastic matrix and the low content of antioxidants and UV stabilizers. In this study, a sodium alginate/MOF-derived magnetic multistage pore carbon material (MIL-101(Fe)/SA-CAs) was developed, having the merits of abundant multistage pore structure, large specific surface area, and good magnetic separation properties. Thus, this material was selected as the sorbent for magnetic solid-phase extraction combined with a dissolution-precipitation method for the extraction and purification of antioxidants and UV stabilizers from polylactic acid food contact plastics. The extraction parameters such as sorbent type, sorbent dosage, sample solution pH, ionic strength, sorption time, elution solution type, volume, and time were investigated. Under the optimized conditions, all the analytes determined by UPLC-MS/MS showed good linear range (r > 0.99), detection limit (0.023–3.105 ng g−1), accuracy (70.6–102.3 %), and reproducibility (RSD<9.8 %). Further, the developed method was applied to determine the antioxidants and UV stabilizers in polylactic acid lunch boxes and straws, showing excellent applicability. The results showed that the antioxidants and UV stabilizers were detected in some of the samples, with a maximum detection of antioxidant 1010 at 7297 ng g−1. This study provided a sensitive, efficient, and environmentally friendly method for antioxidants and UV stabilizers in polylactic acid food contact plastics. The ideas for the design of environmentally friendly metal-organic frameworks and biomass composite multifunctional materials would promise in the sample pretreatment field for the emerging contaminants.

Preparation of mixed-mode weak cation exchange magnetic solid-phase extraction sorbent and its application in the extraction of 21 illicit drugs from wastewater

The detection of illicit drugs in wastewater can effectively monitor and evaluate the trend of illicit drug abuse. A novel mixed-mode cation exchange magnetic sorbent Fe3O4 @poly(ST/DVB/MA-COOH) was prepared and firstly applied as magnetically dispersed solid phase extraction material to efficiently, rapidly, and selectively extract 21 illicit drugs from wastewater. The selectivity of the sorbent was mainly attributed to the electrostatic interaction. The effects of Fe3O4 @poly(ST/DVB/MA-COOH) preparation and extraction conditions on the adsorption performance were thoroughly discussed. Among the 21 illicit drugs, the absolute extraction recovery values for 19 illicit drugs were greater than 80 % and the entire adsorption process could be achieved in one minute. Subsequently, the Fe3O4 @poly(ST/DVB/MA-COOH) sorbent combined with UHPLC-MS/MS was used to establish a quantitative method for the effectively extracted 19 illicit drugs in wastewater. The method had a good determination coefficient in the range of 0.2–200 ng/L and the limits of detection of the method were 0.03–0.67 ng/L. The spiked recovery values were in the range of 87.0–119.6 %. Finally, the method was successfully applied to the detection of 19 illicit drugs in wastewater samples and also compared with the commonly used SPE method. The obtained results indicate that Fe3O4 @poly(ST/DVB/MA-COOH) has great advantages in the detection of illicit drugs in wastewater.

Green preparation of magnetic pyrene-based hyper-cross-linked polymer using dual-purpose ferric chloride reagent for extraction of polycyclic aromatic hydrocarbons from natural water bodies

A magnetic hyper-cross-linked polymer Fe3O4/HCPPYR was prepared using pyrene as the monomer and formaldehyde dimethyl acetal (FDA) as the cross-linking agent. The objective of green chemistry was achieved by employing FeCl3 during the synthesis, as it played a dual role of a catalyst for the Friedel-Crafts reaction and an iron source for the synthesis of magnetic Fe3O4, thus maximizing efficiency and minimizing waste. Fe3O4/HCPPYR was applied as a sorbent for magnetic solid-phase extraction (MSPE) to extract fifteen polycyclic aromatic hydrocarbons (PAHs) from water. The effects of different parameters such as the quantity of adsorbent, the extraction time, the desorption conditions, the pH value and the effect of the salt concentration on the extraction efficiency were optimized. A simple and efficient method in combination with gas chromatography-mass spectrometry (GC–MS) (Fe3O4/HCPPYR−MSPE/GC–MS) was developed and successfully applied for the detection of PAHs in environmental water samples The analytical method showed LODs in the range of 0.004−0.06 µg L−1, which proved to be adequate for the detection all 15 PAHs at trace concentration. Spiked recoveries of PAHs in actual water samples ranged from 85.2 % to 118.5 % with relative standard deviations (RSDs) below 10.2%. These results indicate that the method has a good potential for reusability and possesses excellent sensitivity. This study showcased the potential of Fe3O4/HCPPYR composites in effectively removing organic pollutants from the aqueous environments, demonstrating their ability for water treatment applications.

Synthesis of Modified Magnetic Graphene Oxide with Mesoporous Silica for Extraction of the Pharmaceutical Compound Quercetin.

In this study, magnetic mesoporous silica-Fe3O4-graphene oxide nanoparticles (Fe3O4@GO@mSiO2) were synthesized and used as sorbents for magnetic solid-phase extraction (MSPE) of trace amounts of quercetin in natural samples (spinach, green pepper, dill, and red onion). The sorbent produced was characterized by Fourier transform infrared (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), X-ray diffraction (XRD), vibrating sample magnetometry (VSM), and X-ray photoelectron spectroscopy (XPS). The effects of various experimental factors on the percent recovery of quercetin, including extraction time, desorption time, sample solution pH, and adsorbent amount were investigated. The Fe3O4@GO@mSiO2 strategy showed excellent stability and sensitivity for the determination of quercetin, with a suitable linear range of 20-800 µg L-1 and a detection limit of 5.2 µg L-1. The data indicate that Fe3O4@GO@mSiO2 has a specific surface area and suitable adsorption capacity for the determination of quercetin.

HYBRID ORGANIC–INORGANIC ASSEMBLIES BASED ON COORDINATION METAL–LIGAND FRAGMENTS: SYNTHESIS, PROPERTIES, APPLICATION IN CHROMATOGRAPHY

The data on the synthetic methods of metal-organic frameworks (MOF) based on the coordination compounds of metals, including germanium, with the polydentate aromatic acids, their properties and applications are systemised in the paper. The prospect of using such types of MOFs to determine the highly toxic organic pollutants such as polycyclic aromatic hydrocarbons (PAHs) has been identified. Due to their unique properties, including large surface area, uniformly structured nanoscale cavities, tunable pore sizes and thermal stability MOFs are promising materials for use in analytical chemistry. They have been used in air sampling, as a stationary phase in chromatography, and as sorbents for solid-phase extraction, solid-phase microextraction, and magnetic solid-phase extraction. Depending on the structure of the ligands, MOFs can provide molecular recognition through different types of interactions of a wide range of compounds, such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pyrethroids, nitrosamines and parabens, that are immunosuppressors, endocrine disruptors and cancerogenic compounds. For example, MOFs adsorb hydrophobic organic compounds (e.g., PAHs, PCBs) due to π-π stacking and hydrophobic interactions with organic linkers. Whereas the extraction of organic compounds with hydrophilic groups (for example, nitrosamines) occurs due to electrostatic interaction and hydrogen bonds. The most effective methods of synthesis of the considered type MOF are hydro(solvo)thermal synthesis and mechanochemical methods modified by adding a small amount of solvents. The slow diffusion methods are advisable to use to obtain crystals suitable for single-crystal X-ray diffraction.

Green magnetic snail shell hydroxyapatite sorbent for reliable solid-phase extraction of pesticides from water samples.

To address sustainability issues, the green synthesis of nanomaterials has recently received considerable attention. This article addresses a novel and cost-effective adsorbent for the extraction of eight phenyl-N-methylcarbamate insecticides from water samples. We first synthesized a magnetite/hydroxyapatite nanocomposite using snail shell powder via an environmental friendly approach. The morphology and physicochemical properties of magnetic hydroxyapatite were characterized by Fourier transform infrared spectroscopy, energy-dispersive X-ray spectroscopy, and scanning electron microscopy. Magnetic extraction parameters were optimized using a Doehlert matrix. Under optimum conditions, the magnetic extraction coupled with a LC-MS method shows good linearity with R2 ≥ 0.9982, suitable intra- and interday precision, and limits of detection and quantification in the range of 0.052-0.093μg/L and 0.11-0.31μg/L, respectively. Satisfactory relative recoveries of all carbamates were achieved from fortified water samples in the range of 93.89-101.01%.

Aptamer-modified magnetic nanoparticles for extraction of atrazine in environmental water samples

In this work, a novel aptamer magnetic sorbent was prepared and used as magnetic solid-phase extraction sorbent for selective isolation of atrazine (ATZ) in water samples. The magnetic oligosorbent was fabricated by immobilizing DNA aptamer onto the surface of vinylized magnetic nanoparticles (VMNPs) via “thiol-ene” click chemistry reaction. After optimization of different aptamer coupling parameters, the following experimental conditions were found to give best results: 100 mg VMNPs incubated with 1 μmol L−1 thiol-modified aptamer for 5 h at 55 °C. The resulting oligosorbent was characterized by different instrumental techniques such as transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR) and inductively coupled plasma mass spectrometry (ICP-MS). Then, several parameters of the extraction protocol were investigated to achieve the best ATZ extraction performance. The optimized aptamer-based magnetic solid-phase extraction (Apt-MSPE) protocol followed by HPLC with diode-array detection gave detection and quantification limits for ATZ of 0.005 µg L−1 and 0.018 µg L−1, respectively. The applicability of this protocol was demonstrated by analyzing several environmental water samples from of different sources with recovery values from 85.5 to 94% and relative standard deviations less than 2.5%. Moreover, the developed Apt-MNPs sorbent could be re-used at least 12 times, without losses in its extraction capacity.

A nitrogen-doped graphene tube composite based on immobilized metal affinity chromatography for the capture of phosphopeptides

A novel immobilized metal affinity chromatography (IMAC) functional composite, mNi@N-GrT@PDA@Ti4+, was fabricated based on ultrathin magnetic nitrogen-doped graphene tube (mNi@N-GrT) after chelated Ti4+ with polydopamine, following as a magnetic solid-phase extraction sorbent for rapidly selective enrichment and mass spectrometry identification of phosphorylated peptides. After optimized, the composite exhibited high specificity in the enrichment of phosphopeptides from the digest mixture of β-casein and bovine serum albumin (BSA). The robust method presented the low detection limits (1 fmol, 200 μL) and excellent selectivity (1:100) in the molar ration mixture of β-casein and BSA digests. Furthermore, the selective enrichment of phosphopeptides in the complex bio-samples, was successfully carried out. The results showed that 28 phosphopeptides were finally detected in mouse brain, and 2087 phosphorylated peptides were identified in the HeLa cells extracts with specific selectivity of 95.6%. The enrichment performance of mNi@N-GrT@PDA@Ti4+ was satisfactory, suggesting that the functional composite provided a potential application in the enrichment of trace phosphorylated peptides from the complex biological matrix.

A magnetic solid-phase extraction sorbent based on ionic liquid-derived nitrogen and sulfur co-doped ordered mesoporous carbon for the analysis of triazine herbicides in fruit juices

Developing a novel magnetic mesoporous carbon material with the high surface area, completely open pore system, and sufficient magnetic response for microextraction application is highly desired. In the present work, a magnetic N,S-codoped ordered mesoporous carbon (Fe-GIOMC) was synthesized via nanocasting method using 1-methyl-3-phenethyl imidazolium hydrogen sulfate, guanine, and FeCl3 as the carbon, auxiliary nitrogen, and iron source, respectively. Owing to the intrinsic hydrophobicity of carbon rods, the in-situ incorporation of N and S endows the prepared material the suitable hydrophilicity, which is highly favorable for microextraction of analytes with moderate polarities such as triazine herbicides. The material was characterized by scanning electron microscopy, elemental mapping, nitrogen adsorption–desorption isotherm, Fourier transform infrared spectrometry, Raman spectrometry, and vibrating sample magnetometry. The synthesized Fe-GIOMC was applied for ultra-trace determination of triazine herbicides with low detection limits (0.1–0.3 μg L−1), good RSDs (below 10.6 %), and wide linear ranges (0.5–100 μg L−1). Besides, a considerable re-usability of the Fe-GIOMC sorbent, more than 6 reuses without an observable decrease in the adsorption performance, was obtained. Finally, the Fe-GIOMC was successfully applied for the determination of triazine herbicides from fruit juices.

Synthesis of cellulose nanofibers-based ImSalophen@Fe3O4 as a green sorbent for magnetic solid-phase extraction of chlorophenols followed by quantification via high-performance liquid chromatography-ultraviolet detection

An effective, sensitive, relatively-fast and cost-effective method was developed to determine four types of selected chlorophenols (CPs) including 4-cholorophenol, 2,4-dicholorophenol, 2,5-dicholorophenol and 2,4,6-tricholorophenol in several kinds of honey, black tea and bovine milk samples through applying Cellulose Nano-Fiber (CNF)-ImSalophen@Fe3O4. CNF-ImSalophen@Fe3O4 has been synthesized using a very simple, easy, cost-effective, efficient and fast method. First, a magnetic CNF was used as the substrate. Next, imidazole was created on the surface of the magnetic CNF. Thereafter, the Cl-Salophen Schiff base was accommodated on the prepared magnetic CNF-Im. The prepared sorbent was used for the extraction of selected analytes. The extracted analytes were desorbed via organic solvent and analyzed through high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The strong interactions between the sorbent and the selected analytes (intermolecular hydrogen bonding, and π-π interactions) made this sorbent capable of high extraction performance and capacity. Under the optimized condition, the method linearity was in the range of 0.2–500 µg/L for the selected analytes in water. The calibration curves showed a determination of coefficient higher than 0.9986. The limits of detection and limits of quantification were calculated to be between 0.05–0.14 µg/L and 0.16–0.46 µg/L, respectively. In order to calculate the method precision, the inter-day and intra-day relative standard deviations were determined to be between 3.2 and 4.7 % in three selected concentrations. Furthermore, the enrichment factors were found to be 36, 31, 33 and 37 for 4-cholorophenol, 2,4-dicholorophenol, 2,5-dicholorophenol and 2,4,6-tricholorophenol, respectively. Moreover, the calculated absolute recoveries were between 62 and 74 %. The proposed method was also employed for the analysis of various real samples such as honey, bovine milk and black tea. The obtained recoveries indicated that the method was useful and applicable in complicated real samples.

Magnetic solid-phase extraction of polycyclic aromatic hydrocarbons from water samples using magnetic carbon nanofiber/MIL-101(Cr) nanocomposites.

In this study, magnetic carbon nanofibers (Fe3O4@CNF) were modified with MIL-101(Cr) (Fe3O4@CNF@MIL-101) and used as sorbents for magnetic solid-phase extraction (MSPE) to extract polycyclic aromatic hydrocarbons (PAHs) from real water samples. Gas chromatography coupled with a flame ionization detector (GC-FID) was used for the determination of the PAHs. The effect of experimental variables on the extraction efficiency of PAHs was investigated and optimized. These variables include the quantity of sorbent, the kind and volume of the elution solvent, the duration of extraction and desorption, and the salt concentration. The linear range was found to be 0.01 to 200 ng mL-1 with correlation coefficients ranging from 0.9906 to 0.9931 after the effective extraction parameters were optimized. Its detection limits (LOD) were also calculated to be between 0.003 and 0.005 ng mL-1 (S/N = 3). The method's repeatability was tested at three different concentration levels (0.1, 1, and 10 ng mL-1), and relative standard deviations (RSDs%) were obtained in the range of 2.3 to 5.0%. Finally, using the MSPE-GC-FID method, PAHs were extracted from tap water, wastewater, seawater, and spring water samples. The relative recoveries were in the range of 95.7 to 99.8%.

Determination of four fungicides in water by magnetic solid phase extraction-ultrahigh performance liquid chromatography-tandem mass spectrometry using covalent organic framework material

Fungicides can lead to soil and plant diseases after long-term enrichment in the environment; they can also penetrate deeper into the soil and groundwater by rainwater or irrigation, threatening the water environment and human health. Therefore, it is crucial to develop a simple, rapid, efficient, and sensitive analytical method for the detection of fungicides in the water environment. Sample pretreatment is important for the extraction and enrichment of pollutants from environmental water. Magnetic solid phase extraction (MSPE) is a new sample pretreatment method, which uses magnetic materials as adsorbents dispersed in solution, and rapid separation can be achieved by the aid of external magnets. Because of its advantages of short analytical time, less organic solvent consumption, and easy separation of adsorbents, MSPE has attracted much attention. The key to MSPE is the preparation of highly selective magnetic adsorbents. Covalent organic frameworks have the advantages of large surface area, good chemical and thermal stability, tunable porous structure, low density, and easy functionalization, all of which are ideal for adsorbing fungicides. The concentration of fungicides in environmental water is low. Ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) has high sensitivity and high selectivity, which is suitable for the analysis of fungicides. In this work, a magnetic covalent organic framework Fe3O4@TpBD was prepared by an in situ method, as the MSPE sorbent material to enrich of benzimidazole fungicides (thiabendazole, carbendazim, fuberidazole) and organic sulfur fungicide (isoprothiolane) in environmental water. An extraction method based on π-π conjugation, hydrogen bonding, and electrostatic interaction between Fe3O4@TpBD and the fungicides, in combination with UHPLC-MS/MS, was developed for the determination of four trace fungicides in water. Transmission electron microscopy (TEM), X-ray diffractometry (XRD), and Fourier transform-infrared spectroscopy (FT-IR) were performed to confirm the successful synthesis of Fe3O4@TpBD and to characterize this material. A series of experiments were carried out to decide the optimal extraction conditions, i. e., the magnetic ratio and dosage of Fe3O4@TpBD, pH of the water sample, adsorption time, type and volume of the eluent, elution time, and salinity. Gradient elution was carried out with methanol-water as the mobile phase. The target analytes were separated on an ACQUITY UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm), and multiple reaction monitoring (MRM) was conducted in the positive electrospray ionization mode. The ion source temperature and ion source voltage were set to 500 ℃ and 5 kV, respectively. The analytical method was established under the optimized extraction conditions. The four fungicides showed good linearity in the range of 3-1200 ng/L, with linear correlation coefficients greater than 0.998. The limits of detection (LODs) and limits of quantification (LOQs) of this developed method were 0.06-0.28 ng/L and 0.20-0.92 ng/L, respectively. Recovery tests were performed at three spiked levels of 15, 150, and 600 ng/L, with relative standard deviations of 2.8% to 10.0% (intra-day) and 4.4% to 15.7% (inter-day). The accuracy of the established analytical method was investigated by using it to test real water samples, and satisfactory recoveries for the four analytes were achieved within 77.1% to 119.1%. Trace amounts of carbendazim were detected in the reservoir water at 27.5 ng/L. The method has good sensitivity, accuracy, and precision, and the operation process is convenient.

Poly Schiff-base based on polyimides functionalized with magnetic nanoparticles as novel sorbent for magnetic solid-phase extraction of non-steroidal anti-inflammatory drugs in environmental water samples

A core-shell structure of hydroxy-functionalized Schiff-base based on polyimides (PSB) modified with magnetic nanoparticles (Fe3O4@PSB) has been synthesized. The Fe3O4@PSB was employed as a magnetic solid-phase extraction (MSPE) sorbent for the extraction and determination of trace non-steroidal anti-inflammatory drugs (NSAIDs) i.e. naproxen, diclofenac, and ibuprofen in environmental samples followed by high-performance liquid chromatography (HPLC). The structure of Fe3O4@PSB was characterized by TEM, TGA, VSM, EDS mapping, FT-IR, 1H NMR, and 13C NMR analyses to confirm the immobilization of Fe3O4 on PSB. The effective factors, such as desorption solvent, sorbent amount, extraction and desorption time, ionic strength, and sample pH were tuned to obtain the optimal extraction conditions. The calibration curve is linear in the range of 0.05–300 ng mL−1 and the relative standard deviation (RSD) is 3.5–5.5 % under optimal conditions. The limit of detection (LOD) is 0.01–0.03 ng mL−1. The relative spiked recoveries of real water samples ranged from 96.4 to 99.5%, with RSD varying from 5.0 to 6.7%. In real water samples, Fe3O4@PSB demonstrated excellent NSAID adsorption, stability, and reproducibility properties.

Correction to: Gelatin microsphere coated Fe3O4@graphene quantum dots nanoparticles as a novel magnetic sorbent for ultrasound-assisted dispersive magnetic solid-phase extraction of tricyclic antidepressants in biological samples

Correction to: Gelatin microsphere coated Fe3O4@graphene quantum dots nanoparticles as a novel magnetic sorbent for ultrasound-assisted dispersive magnetic solid-phase extraction of tricyclic antidepressants in biological samples