Solid-phase Extraction Adsorbent Research Articles

Preconcentration and Removal of Lead From Water Samples Using Magnetic Copper Ferrite Nanoparticles

The presence of lead and its compounds is extremely dangerous to various forms of life. Therefore, exploring effective treatments that can reduce the presence of lead ions around us becomes crucial, thereby averting lead toxicity. A magnetic solid phase extraction (MSPE) procedure for the removal and preconcentration of trace amounts of Pb(II) using copper ferrite nanoparticles (CuFe2O4 NPs) prior to their determination by flame atomic absorption spectrometry (FAAS) has been proposed. CuFe2O4 as solid-phase extraction adsorbent was synthesized via co-precipitation and characterized by attenuated total reflection–infrared spectroscopy (ATR–IR), x-ray diffraction spectrometry (XRD), and scanning electron microscopy (SEM). These magnetic CuFe2O4 carrying the Pb(II) could be easily separated from the aqueous solution by applying an external magnetic field; no filtration or centrifugation was necessary. Various analytical parameters, including pH, eluent type/concentration, adsorbent mass, sample volume, adsorption/desorption time, mixing, and interfering ions, were systematically studied and optimized for the recovery of Pb(II). A sample volume of 20 mL achieved a preconcentration factor of 20. The method effectively determined Pb(II) in water samples, with recovery values exceeding 95% using the optimal conditions.

Affordable cellulose-based solid phase extraction adsorbent for efficient chromatographic analysis of trace contaminants in environmental waters for developing countries

The current work reports on a new low-cost solid phase extraction (SPE) material obtained by crosslinking cellulose with 4,4–methylenebisphenyldiisocyanate (CMDI-1) for the pre-concentration of two contaminants of emerging concern (CEC): Chloramphenicol (CAP) and Bisphenol-A (BPA) from water. The results obtained show good analytical performance with low Limit of Detection of 71.9 ng/L and 10 ng/L for the pre-concentration of CAP and BPA respectively, and a good linear range between 0.5 and 8 µg/L, with r2 values > 0.99. The application of the developed method for the analysis of real water samples achieved good percentage recoveries (86.8 – 96.2 %), comparable to that of an expensive commercial HLB adsorbent (89.8 – 107 %). Response Surface Methodology modelling indicates that adsorbent dose, elution volume, and sample volume had a significant influence on CAP recovery, while solution pH, elution volume, and ionic strength had a significant influence on BPA recovery. From our economic assessment, a pack of 30 SPE tubes of 500 mg CMDI-1 SPE adsorbent will cost 82 % less than a similar amount of Oasis HLB adsorbent. This study demonstrates and validates a feasible and inexpensive approach to the use of cellulose to develop low-cost SPE adsorbents for the effective pre-concentration and determination of trace contaminants in water. The CMDI-1 SPE adsorbent can be easily prepared and adopted for use by water professionals in developing countries to enhance understanding on the presence and fate of such contaminants in the environment and also in technical systems, towards developing relevant environmental protection measures for sustainability.

Magnetic graphene oxide functionalized dimercaptosuccinic acid/putrescine as a selective and stable solid-phase extraction adsorbent for preconcentration and speciation of arsenic (III) in water samples

ABSTRACT It is challenging for environmental scientists to identify the trace value of arsenite (As(III)) as an essential hazardous material in the presence of arsenate (As(V)) and other metal ions. This paper proposes a method of magnetic solid-phase extraction (MSPE) for the trace analysis of As(III) using magnetite graphene oxide (MGO) covalently functionalised with dimercaptosuccinic acid (DMSA) and putrescine (PUT). The hydrothermally synthesised MGO/DMSA-PUT adsorbent was carefully characterised by using energy-dispersive X-ray spectroscopy analysis, Fourier transform infrared, dynamic light scattering, scanning electron microscopy, zeta potential analyser, X-ray diffraction, and vibrating sample magnetometer techniques in detail. Maximum adsorption capacity of MGO/DMSA-PUT for As(III) was determined 144 mg g−1 which considerably improved vs. graphene oxide with the adsorption capacity of 54.8 mg g−1. Sample pH of 6 with a volume of 50 mL, contact time of 5 minutes, initial concentration of 50 μg L−1, adsorbent dosage of 0.1 g and volume of eluent 3 mL were obtained as the optimised parameters for the developed MSPE procedure. According to experimental data obtained with hydride generation atomic absorption spectroscopy, the linear range and detection limit of the proposed method for As(III) measurement was found to be 0.4–5000 µg L−1 and 9.914 ng L−1, respectively. According to experimental results, a preconcentration limit (PL) of 1.72 µg L−1 was achieved for As(III), corresponding to a preconcentration factor of 965. Statistical analysis of standard reference materials confirmed the accuracy of the method against systematic and constant errors (>95% recovery with <5% RSD). Because of the selectivity of MGO/DMSA-PUT towards the As(III), the developed MSPE procedure is capable for successful speciation and determination of As(III) in water samples with satisfactory analytical results.

Rapidly enrichment and detection of per-and polyfluoroalkyl substances in foods using a novel bifunctional covalent organic framework

Per- and polyfluoroalkyl substances (PFASs) are extensively found in foods, posing potential toxicity to humans. Therefore, rapid analysis and monitoring of PFASs in foods are crucial for public health and also a challenge. To detect trace PFASs in foods, construction of sorbents with multiple interactions could be an effective approach. Herein, a cationic-fluorinated covalent organic framework (CF-COF) was prepared by post-modification and used as a magnetic solid-phase extraction adsorbent for adsorption of PFASs. By combining magnetic solid-phase extraction based on CF-COF with liquid chromatography−tandem mass spectrometry (LC − MS/MS), a novel method was developed for determination of eight long-chain PFASs in foods. Under optimized conditions, the method exhibited low detection limits (0.003–0.019 ng/g) and satisfactory recovery rates (73.5–118%) for PFASs. This study introduces a novel idea for the development of adsorbents targeting PFASs, along with a new analytical method for monitoring of PFASs in foods.

Application of surface-imprinted polymers in pretreatment for detection of sulfamonomethoxine in water samples

A novel surface molecularly imprinted polymer, NH2-MIL-125@MIPs (formed by wrapping a molecularly imprinted polymer around the surface of a MOF carrier NH2-MIL-125) was successfully synthesized by using sulfamonomethoxine as the template. It was used as the adsorbent for solid-phase extraction of sulfonamide antibiotics. The morphology and structure of this polymer was characterized. The polymer was used as the column packing for the homemade solid phase extraction column. The solid phase extraction conditions were optimized to obtain the optimal operation parameters. A method for the detection of trace sulfonamide antibiotics in water was established. The method was evaluated with good linearity in the range of 0.01 μg mL−1 –5.00 μg mL−1. The recoveries of eight SAs ranged from 89.7 % to 107.0 % at the spiked levels of 1, 2 and 3 μg mL−1, and the relative standard deviations of 6 repetitive experiments for eight SAs are always less than 10 %. Real sample results demonstrated that the homemade solid-phase extraction column could be successfully applied to pretreat and quantify sulfonamide in aqueous samples at a trace level.

Magnetic polyimide nanocomposite for analysis of parabens in cooking wine by magnetic solid-phase extraction coupled with gas chromatography – Mass spectrometry

A magnetic polyimide (PI) nanocomposite has been synthesized by phase inversion of PI and simultaneous encapsulation of Fe3O4 nanoparticles. The Fe3O4/PI nanocomposite was characterized by a variety of characterization techniques, including infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption-desorption isotherms, and vibrating sample magnetometry. The results showed that the prepared nanocomposite had a homogeneous structure, adequate specific surface area (76.1 m2/g) and high saturation magnetization (42.9 emu/g). Using parabens as model analytes, the performance of the Fe3O4/PI nanocomposite as an adsorbent for magnetic solid-phase extraction (MSPE) was evaluated. The extracted parabens were desorbed and determined by gas chromatography–mass spectrometry (GC–MS). The parameters affecting the extraction and desorption efficiency of parabens were optimized. Under the optimal conditions, the developed MSPE/GC–MS method was successfully applied to the determination of parabens in cooking wine. The MSPE/GC–MS method exhibited broad linearity (0.2–100 µg/L), low detection limits (0.04–0.05 µg/L), and satisfactory extraction recoveries (79.2 %–113.3 %) with relative standard deviations (RSDs) ranging from 0.7 % to 10.4 %. For real cooking wine samples, the spiked recoveries ranged from 91.7 % to 118.7 % with RSDs of 1.0 %–11.2 %. The results demonstrated that the Fe3O4/PI nanocomposite was an effective adsorbent, and this work provides a novel reference for the easy preparation of magnetic adsorbent materials.

Selective Removal of Chlorophyll and Isolation of Lutein from Plant Extracts Using Magnetic Solid Phase Extraction with Iron Oxide Nanoparticles.

In recent years, there has been a growing interest in plant pigments as readily available nutraceuticals. Photosynthetic pigments, specifically chlorophylls and carotenoids, renowned for their non-toxic antioxidant properties, are increasingly finding applications beyond their health-promoting attributes. Consequently, there is an ongoing need for cost-effective methods of isolation. This study employs a co-precipitation method to synthesize magnetic iron oxide nanoparticles. Scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS) confirms that an aqueous environment and oxidizing conditions yield nanosized iron oxide with particle sizes ranging from 80 to 140 nm. X-ray photoelectron spectroscopy (XPS) spectra indicate the presence of hydrous iron oxide FeO(OH) on the surface of the nanosized iron oxide. The Brunauer-Emmett-Teller (BET) surface area of obtained nanomaterial was 151.4 m2 g-1, with total pore volumes of pores 0.25 cm3 g-1 STP. The material, designated as iron oxide nanoparticles (IONPs), serves as an adsorbent for magnetic solid phase extraction (MSPE) and isolation of photosynthetic pigments (chlorophyll a, lutein) from extracts of higher green plants (Mentha piperita L., Urtica dioica L.). Sorption of chlorophyll a onto the nanoparticles is confirmed using UV-vis spectroscopy, Fourier transform infrared photoacoustic spectroscopy (FT-IR/PAS), and high-performance liquid chromatography (HPLC). Selective sorption of chlorophyll a requires a minimum of 3 g of IONPs per 12 mg of chlorophyll a, with acetone as the solvent, and is dependent on a storage time of 48 h. Extended contact time of IONPs with the acetone extract, i.e., 72 h, ensures the elimination of remaining components except lutein, with a spectral purity of 98%, recovered with over 90% efficiency. The mechanism of chlorophyll removal using IONPs relies on the interaction of the pigment's carbonyl (C=O) groups with the adsorbent surface hydroxyl (-OH) groups. Based on molecular dynamics (MD) simulations, it has been proven that the selective adsorption of pigments is also influenced by more favorable dispersion interactions between acetone and chlorophyll in comparison with other solutes. An aqueous environment significantly promotes the removal of pigments; however, it results in a complete loss of selectivity.

Porous poly(bismaleimide-co-divinylbenzene) microspheres as dispersive solid-phase extraction adsorbent coupled to high-performance liquid chromatography for the determination of triazine herbicide residues in vegetable samples.

In this work, monodisperse and nano-porous poly(bismaleimide-co-divinylbenzene) microspheres with large specific surface area (427.6 m2 /g) and rich pore structure were prepared by one-pot self-stable precipitation polymerization of 2,2'-bis[4-(4-maleimidophenoxy) phenyl] propane and divinylbenzene. The prepared poly(bismaleimide-co-divinylbenzene) microspheres were employed as dispersive solid-phase extraction (DSPE) adsorbent for the extraction of triazine herbicides. Under optimized conditions, good linearities were obtained between the peak area and the concentration of triazine herbicides in the range of 1-400µg/L (R2 ≥ 0.9987) with the limits of detection of 0.12-0.31µg/L. Triazine herbicides were detected using the described approach in vegetable samples (i.e., cucumber, tomato, and maize) with recoveries of 93.6%-117.3% and relative standard deviations of 0.4%-3.5%. In addition, the recoveries of triazine herbicides remained above 80.7% after being used for nine DSPE cycles, showing excellent reusability of poly(bismaleimide-co-divinylbenzene) microspheres. The adsorption of poly(bismaleimide-co-divinylbenzene) microspheres toward triazine herbicides was a monolayer and chemical adsorption. The adsorption mechanism between triazine herbicides and adsorbents might be a combination of hydrogen bonding, electrostatic interaction, and π-π conjugation. The results confirmed the potential use of the poly(bismaleimide-co-divinylbenzene) microspheres-based DSPE coupled to the high-performance liquid chromatography method for the detection of triazine herbicide residues in vegetable samples.

Sustainable bio-based solid phase extraction adsorbent for the determination of various types of organic compounds.

A sustainable, bio-based, mesoporous material, Starbon A800, was explored for use as an adsorbent in solid phase extraction (SPE). A solution containing seven nitrosamines was first used as a standard to optimise conditions for extraction efficiency with Starbon A800. After optimising conditions, 25 compounds of varying polarity (terpenes, phenolics, pesticides, PAHs, amines, and nitrosamines) were extracted with SPE using either Starbon® A800, C18 or Porous Graphitic Carbon (PGC) as the adsorbent, for comparison purposes. At the same time, 3 different elution solvents (heptane, dichloromethane, and ethanol) were used for each type of adsorbent. Hansen solubility parameters can be used to choose an appropriate elution solvent for the selected SPE adsorbent. The best average SPE recoveries found for the 25 various compounds were 83%, 79%, and 65% using Starbon A800, PGC, and C18 adsorbents respectively and these had dichloromethane as the elution solvent. The identification and quantification of components was carried out using UV-visible spectroscopy, two-dimensional gas chromatography (GCxGC) with time of flight/mass spectrometry (TOF/MS) or a nitrogen chemiluminescence detector (NCD). The optimized method was successfully applied to extract volatile organic compounds from red wine and tap water using Starbon A800. Starbon A800 was shown to be a promising, low-cost, green, scalable, alternative adsorbent for the extraction of various types of organic compounds of a wide range of polarities using SPE.

Magnetic dummy-template molecularly imprinted polymer with an ultrathin shell for selective enrichment of geosmin in water sample

A dummy-template molecularly imprinted polymer (DMIP) based on magnetic carbon nanotubes was synthesized. The eluted polymers with an improved ultrasound assisted/oscillating (magnetic separation) method were successfully employed for the adsorption and separation of geosmin (GSM), an odorous compound in eutrophic waterbodies. The properties of the obtained composite materials were evaluated through a series of morphological and physicochemical characterization. The results showed that a thin and uniform imprinted shell (∼10–15 nm) effectively coated the surface of magnetic carbon nanotubes, exhibiting good adsorption efficiency and magnetic functionality. The binding performance and selectivity of Mag-MWCNTs @DMIPs as adsorbents for GSM were evaluated and compared with non-imprinted polymers. The maximum adsorption capacity of polymers for GSM, as determined by the Langmuir model, is 18.71 mg g−1, which adsorption equilibrium reached in approximately 45 min. The adsorption thermodynamic parameters ΔG shown that the adsorption process was spontaneous. Selectivity and regeneration experiment further demonstrated the ability of Mag-MWCNTs @DMIPs to selectively separate trace GSM from complex matrices. The polymer obtained in this study can be used as an adsorbent for magnetic dispersion solid-phase extraction to preconcentration of trace GSM in natural water, facilitating the measurement of GSM.

Pore Size Adjustment Strategy for the Fabrication of Molecularly Imprinted Covalent Organic Framework Nanospheres at Room Temperature for Selective Extraction of Zearalenone in Cereal Samples.

Covalent organic frameworks (COFs) are attractive adsorbents for sample pretreatment due to their unique structure and properties. However, the selectivity of COFs for the extraction of hazardous compounds is still limited due to the lack of specific interactions between COFs and targets. Herein, we report a pore size adjustment strategy for room-temperature synthesis of molecularly imprinted COF (MICOF) for selective extraction of zearalenone (ZEN) in complex food samples. The three-dimensional building block tetra(4-aminophenyl) methane was used as a functional monomer, while dialdehyde monomers with different numbers of benzene ring were used to adjust the pore size of MICOF to match with the size of ZEN molecules. The prepared MICOF gave the largest adsorption capacity of 177.2 mg g-1 and the highest imprinting factor of 10.1 for ZEN so far. MICOF was used as the adsorbent for dispersed solid-phase extraction in combination with high-performance liquid chromatography for the determination of trace ZEN in cereals. The high selectivity of the developed method allows simple aqueous standard calibration for the matrix effect-free determination of ZEN in food samples. The limit of detection and the recoveries of the developed method were 0.21 μg kg-1 and 93.7-101.4%, respectively. The precision for the determination of ZEN was less than 3.8% (RSD, n = 6). The developed method is promising for the selective determination of ZEN in complex matrices.

MIL-53/UiO-66/PAN beads as a novel adsorbent for simultaneous extraction of trace pesticides in wheat, wheat flour and field soil followed by GC-MS analysis

To develop a facile, efficient and sensitive method for simultaneous determination of multiple pesticides in wheat, wheat flour and field soil, a novel MIL-53/UiO-66/PAN bead was successfully prepared and applied as adsorbent in a simplified dispersive solid-phase extraction (d-SPE) followed by GC-MS analysis. Moreover, the MIL-53/UiO-66/PAN bead could be directly separated owing to its scale of millimeter, which overcome the shortcomings of traditional d-SPE. After optimization of key factors by Response Surface Methodology, the proposed method exhibited excellent linearity (R2> 0.99) and detection limits of 0.17-1.21µg/L. Furthermore, recoveries were in range of 77.8-98.3%, with RSDs lower than 9.2%. Finally, the developed method was successfully applied to the determination of pesticides in wheat, wheat flour and soil from wheat field, where Triadimefon was detected in wheat and soil samples at a concentration of 28.7 and 36.9µg/kg, respectively. The results demonstrated that the MIL-53/UiO-66/PAN-based d-SPE-GC-MS method provided a more convenient strategy for efficient extraction and determination of pesticides in wheat, wheat flour and field soil.

Facile Preparation of Magnetic COF-on-COF for Rapid Adsorption and Determination of Sulforaphane from Cruciferous Vegetables

Sulforaphane (SFN) is a natural isothiocyanate compound widely abundant in cruciferous vegetables with multiple bioactive functions. However, traditional analytical methods for the extraction and determination of SFN are cumbersome, time-consuming, and low sensitivity with large amounts of organic solvents. Herein, novel magnetic COF-on-COFs (MB-COFs) were fabricated using Fe3O4 as a magnetic core and COFs-1 grown with COFs-2 as a shell, and they were used as efficient adsorbents of magnetic dispersive solid-phase extraction for rapid quantification of SFN in cruciferous vegetables by combining with HPLC-MS/MS. At the optimal ratio of COFs-1 to COFs-2, MB-COFs had a spherical cluster-like structure and a rough surface, with a sufficient magnetic response for rapid magnetic separation (1 min). Due to the introduction of Fe3O4 and COFs-2, MB-COFs exhibited outstanding extraction efficiencies for SFN (92.5–97.3%), which was about 18–72% higher than that of the bare COFs. Moreover, MB-COFs showed good adsorption capacity (Qm of 18.0 mg/g), rapid adsorption (5 min) and desorption (30 s) to SFN, and favorable reusability (≥7 cycles) by virtue of their unique hierarchical porous structure. The adsorption kinetic data were well fitted by the pseudo-second-order, Ritchie-second-order, intra-particle diffusion, and Elovich models, while the adsorption isotherm data were highly consistent with the Langmuir, Temkin, and Redlich–Peterson models. Finally, under the optimized conditions, the developed method showed a wide linear range (0.001–0.5 mg/L), high sensitivity (limits of quantification of 0.18–0.31 μg/L), satisfactory recoveries (82.2–96.2%) and precisions (1.8–7.9%), and a negligible matrix effect (0.82–0.97). Compared to previous methods, the proposed method is faster and more sensitive and significantly reduces the use of organic solvents, which can achieve the efficient detection of large-scale samples in practical scenarios. This work reveals the high practical potential of MB-COFs as adsorbents for efficient extraction and sensitive analysis of SFN in cruciferous vegetables.

Magnetic solid-phase extraction-based surface-enhanced Raman spectroscopy for label-free therapeutic drug monitoring of carbamazepine and clozapine in human serum

Determination of antiepileptic drugs and antipsychotics in human serum is significant in individualized drug administration and therapeutic drug monitoring (TDM). In this study, we developed a rapid label-free TDM method for the antiepileptic drug carbamazepine (CBZ) and the antipsychotic clozapine (CLO) in human serum. This detection strategy is based on the combination of surface-enhanced Raman scattering (SERS) and magnetic solid-phase extraction (MSPE). Initially, Fe3O4@SiO2@MIL-101(Fe) nanocomposites were synthesized by the layer-by-layer self-assembly method and characterized using scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Brunauer–Emmett–Teller, ultraviolet–visible, and Fourier transform infrared analyses. Subsequently, CBZ and CLO were detected in human serum using Fe3O4@SiO2@MIL-101(Fe) as the solid-phase extraction adsorbent and Ag nanoparticles as SERS substrates. The potential of the MSPE–SERS method for the label-free TDM of CBZ and CLO was then investigated. Fe3O4@SiO2@MIL-101(Fe) prevents magnetic particle aggregation and demonstrates rapid magnetic separation capability that simplifies the pretreatment process and reduces interference from complex matrices. Its large surface area can effectively enrich targets in complex matrices, thereby improving the SERS detection sensitivity. The linearity between CBZ and CLO was excellent over the concentration range of 0.1–100 µg/mL (calculated as the intensity of the SERS characteristic peaks of CBZ and CLO at 728 cm and 1054 cm−1, respectively), with correlation coefficients (R2) of 0.9987 and 0.9957, and detection limits of 0.072 and 0.12 µg/mL, respectively. The recoveries of CBZ with CLO ranged from 94.0 % to 105.0 %, and their relative standard deviations were <6.8 %. Compared to other assays, the developed MSPE–SERS method has the advantages of simple sample pretreatment, rapid detection, and good reproducibility, which provides a novel approach for the TDM of other drugs.

Carboxyl-functionalized magnetic amide-linked covalent organic framework for efficient extraction of multi-class mycotoxins from soybeans prior to HPLC-MS/MS analysis

Mycotoxins co-contamination in soybean poses great risks to human health, however, due to their diverse structures, it is difficult to simultaneously extract and detect these multi-mycotoxins. By incorporating modification of hydrophilic carboxyl groups with the hydrophobic properties of covalent organic frameworks, a stable cubic carboxyl-functionalized magnetic amide-linked covalent organic framework were fabricated, characterized and utilized as adsorbents for magnetic solid phase extraction (MSPE) of eleven frequently detected mycotoxins from soybeans followed by HPLC-MS/MS analysis. The key MSPE parameters were screened using the Plackett-Burman design and optimized with the Box-Behnken design for response surface methodologies. Under the optimal experimental conditions, the linear range was 0.2–50 μg/kg, the limits of detection were 0.1–1.4 μg/kg. The established method was applied for the soybean analysis with satisfactory recoveries (70.8–108.3%) and precision (intra- and inter-relative standard deviations of 2.1–9.2% and 1.6–11.1%, respectively). With proper modification, this method may have great application potential for simultaneously analyzing and monitoring the multi-mycotoxin contamination in foods to ensure consumer safety and public health.

In situ growth of ZIF-67 to construct core-shell mosaic structural composites for efficient extraction of benzoylurea insecticides.

A novel mosaic structure Silica@C/Co@ZIF-67 composite was synthesized by successfully embedding Co nanoparticles on the surface of silica spheres with the help of thermoplastic polyethyleneimine by carbon-reduction. The ZIF-67 half-shell layer structure was synthesized by the in-situ growth of ZIF-67 on the surface of silica spheres through the coordination of 2-methylimidazole with Co metal nodes. The composite was used as a magnetic solid-phase extraction adsorbent combined with high performance liquid chromatography-ultraviolet detector (HPLC-UV) for the extraction and determination of benzoylurea insecticides (BUs) in vegetables and tea. Based on the presence of π-π, hydrophobic and hydrogen bonding interactions between Silica@C/Co@ZIF-67 and BUs, the BUs were rapidly captured by the composites resulting in high adsorption performance. Under the optimal extraction parameters, the linear ranges were 0.3-200µg L-1 for diflubenzuron, 0.6-200µg L-1 for chlorbenzuron, and 1.0-200µg L-1 for triflumuron, teflubenzuron, and flufenoxuron, with correlation coefficients (R2) greater than 0.9991. The limits of detection (LODs) of the method were 0.1-0.3μg L-1, and the relative standard deviations (RSDs) were 1.2-3.0% for intra-day and 2.6-4.6% for inter-day. In the spiked recovery experiments of vegetables and tea, the recoveries of the five kinds of BUs ranged from 75.8 to 112.9%. In addition, after 10 repetitions using Silica@C/Co@ZIF-67, the recoveries of the five kinds of BUs were still as high as 78.4 to 83.9%.

Magnetic molecularly imprinted polymers integrated ionic liquids for targeted detecting diamide insecticides in environmental water by HPLC-UV following MSPE

Efficiently detecting diamide insecticides in environmental water is challenging due to their low concentrations and complex matrix interferences. In this study, we developed ionic liquids (ILs)-incorporated magnetic molecularly imprinted polymers (IL-MMIPs) for the detection of diamide insecticides, capitalizing on the advantages of ILs and quick magnetic separation through surface imprinting. Tetrachlorantraniliprole was used as the template, and a specific IL, 1-vinyl-3-ethylimidazolium hexafluorophosphate ([VEIm][PF6]), was employed as the functional monomer. Various synthesis conditions were investigated to optimize adsorption efficiency. The prepared IL-MMIPs were successfully employed as adsorbents in magnetic solid-phase extraction (MSPE) to selectively extract, separate, and quantify three types of diamide insecticides from water samples using HPLC-UV detection. Under optimal conditions, the analytical method achieved low limits of detection (0.69 ng mL−1, 0.64 ng mL−1, 0.59 ng mL−1 for cyantraniliprole, chlorantraniliprole and tetrachlorantraniliprole, respectively). The method also displayed a wide linear range (0.003–10 μg mL−1 for cyantraniliprole and chlorantraniliprole, and 0.004–10 μg mL−1 for tetrachlorantraniliprole, respectively) with satisfactory coefficients (R2≥0.9996), and low relative standard deviation (RSD≤2.55%). Additionally, extraction recoveries fell within the range of 79.4%–109%. The results clearly demonstrate that IL-MMIPs exhibit exceptional recognition and rebinding capabilities. The developed IL-MMIPs-MSPE-HPLC-UV method is straightforward and rapid, making it suitable for the detection and analysis of three kinds of diamide insecticides in environmental water.

Developing a novel magnetic organic polymer for selective extraction and determination of 16 macrolides in water and honey samples.

A novel magnetic organic polymer Fe3O4@SiO2@Tb-PDAN was designed and synthesized, which was used as an adsorbent for magnetic solid-phase extraction (MSPE) of 16 macrolides (MALs) in water and honey. The synthesized adsorbent was characterized using techniques including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Then several parameters of the extraction process were further optimized. Under the optimized conditions, an MSPE-LC-MS/MS method was established for extraction and determination of 16 MALs, which showed good linearity (r ≥ 0.999), low limits of detection (0.001-0.012 μg L-1 for water and 0.001-0.367 μg kg-1 for honey) and satisfactory recoveries (70.02-118.91%) with the relative standard deviations (RSDs) lower than 10.0%. This established method was then successfully applied to detect MALs in real samples, which suggested that Fe3O4@SiO2@Tb-PDAN was a potential magnetic adsorbent for efficient extraction and analysis of MALs.

A water compatible magnetic molecularly imprinted nanocomposite for the class-selective enrichment of quinoxaline-1,4-dioxides in environmental water.

In this work, a novel water compatible core-shell magnetic molecularly imprinted nanocomposite (Fe3O4-COOH@MIPs) was synthesized in an acetonitrile-water reaction system by adopting carboxyl group-functionalized Fe3O4 nanoparticles as the magnetic core, olaquindox as the template molecule and acrylamide as the functional monomer. The resulting Fe3O4-COOH@MIPs was characterized and applied as an adsorbent for magnetic solid-phase extraction (MSPE) of three quinoline-1,4-dioxides (QdNOs). The Fe3O4-COOH@MIPs possessed strong magnetic responsiveness, fast adsorption equilibrium rate (equilibrium within 5 min) and excellent selectivity. By coupling Fe3O4-COOH@MIPs based MSPE with high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), good linearity (R2 ≥ 0.9985) and low limits of detection (0.83-5.0 ng L-1) for QdNOs were obtained. Finally, the proposed method was applied to determine trace QdNOs in environmental water samples, and the recoveries were in the range of 68.08-99.88% with RSD less than 12.5%.

The preparation of a boronate affinity-based controlled oriented imprinting coating on a silica nanoparticle surface for the separation and purification of shikimic acid in herbal medicine.

Shikimic acid (SA) is one of the most effective drugs against the A (H1N1) virus and has high medicinal value. Additionally, it has the ability to generate non-toxic herbicides and antimicrobial medications. The extraction from plants has proven to be the main route of production of SA with economic benefits and environmental efficiency. Therefore, it is necessary to perform purification of SA from these herbal medicines before quantifying it. In this study, researchers employed a boronate affinity-based controlled oriented surface imprinting technique to produce molecularly imprinted polymers (MIPs) as highly effective solid phase extraction (SPE) adsorbents for the isolation and purification of SA. 3-Fluoro-4-formylphenylboronic acid functionalized silica nanoparticles were used as supporting materials for immobilizing SA. Poly(2-anilinoethanol) with a higher hydrophilic domain can be used as an effective imprinting coating. The prepared SA-imprinted silica nanoparticles exhibited several significant results, such as good specificity, high binding capacity (39.06 ± 2.24 mg g-1), moderate binding constant (6.61 × 10-4 M-1), fast kinetics (8 min) and low binding pH (pH 5.0) toward SA. The replication of SA-imprinted silica nanoparticles was deemed satisfactory. The SA-imprinted silica nanoparticles could be still reused after seven adsorption-desorption cycles, which indicated high chemical stability. In addition, the recoveries of the proposed method for SA at three spiked level analysis in star aniseed and meadow cranesbill were 96.2% to 109.0% and 91.6% to 103.5%, respectively. The SA-imprinted silica nanoparticles that have been prepared are capable of identifying the target SA in real herbal medicines. Our approach makes sample pre-preparation simple, fast, selective and efficient.