Magnetic γ-cyclodextrin polymer with compatible cavity promote the magnetic solid-phase extraction of microcystins in water samples

Microcystin-LR in drinking water: An emerging role of mitochondrial-induced epigenetic modifications and possible mitigation strategies

Algal blooms are a serious menace to freshwater bodies all over the world. These blooms typically comprise cyanobacterial outgrowths that produce a heptapeptide toxin, Microcystin-LR (MC-LR). Chronic MC-LR exposure impairs mitochondrial-nuclear crosstalk, ROS generation, activation of DNA damage repair pathways, apoptosis, and calcium homeostasis by interfering with PC/MAPK/RTK/PI3K signaling. The discovery of the toxin's biosynthesis pathways paved the way for the development of molecular techniques for the early detection of microcystin. Phosphatase inhibition-based bioassays, high-performance liquid chromatography, and enzyme-linked immunosorbent tests have recently been employed to identify MC-LR in aquatic ecosystems. Biosensors are an exciting alternative for effective on-site analysis and field-based characterization. Here, we present a synthesis of evidence supporting MC-LR as a mitotoxicant, examine various detection methods, and propose a novel theory for the relevance of MC-LR-induced breakdown of mitochondrial machinery and its myriad biological ramifications in human health and disease.

Interface-assisted synthesized covalent organic framework film for efficient extraction of microcystins in aquatic organisms

Covalent organic framework (COF) film-based solid-phase extraction (F-SPE) has garnered great attention in sample pretreatment. However, harsh synthesis conditions of COF films have severely hindered their potential applications. In this study, a kind of COF (TPB-DMTP) films were fabricated via a liquid-liquid interfacial synthesis method at a mild condition. The obtained films exhibited excellent extraction performance towards microcystins (MCs, an algal toxin) due to their porous structure, high specific surface area and abundant accessible adsorption sites. Coupled TPB-DMTP films-based F-SPE with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), a sensitive and environment-friendly analytical method was established for MCs detection. Under the optimal conditions, this method possessed wide linear ranges (2.0-800.0 pg mL-1) with good linearity (R ≥ 0.9991), low limits of detection (0.8-3.0 pg mL-1) and satisfactory precision (RSDs ≤7.1 %), which then successfully applied for MCs detection in actual aquatic organism samples. Trace amounts of MC-RR (42.4 pg mL-1) and MC-YR (14.6 pg mL-1) were detected in the mussels. The results demonstrate the excellent application potential of COF films in sample pretreatment.

β-Cyclodextrin/calix[4]arene hybrid porous organic polymer membrane for synergistic extraction of fluorescent whitening agents migrating from food contact materials

Acurate and sensitive determination of hazards from food contact materials is important to monitor food safety. It is necessary to excavate efficient adsorbent for simultaneous recognition and adsorption of food hazards of trace level for sample preparation. In this work, β-cyclodextrin and calix[4]arene were employed as hybrid functional monomers to prepare macrocyclic porous organic polymer (β-CD-CX4 POP). It was proved that the supramolecular cavities of β-CD-CX4 POP could form inclusion complexes with fluorescent whitening agents (FWAs) through host-guest recognition, which greatly improved the adsorption performance. The hydrophobic cavities of β-cyclodextrin and calix[4]arene of β-CD-CX4 POP exhibited synergistic effect for simultaneous recognition of FWAs. The high-throughput enrichment of FWAs was realized by β-CD-CX4 POP membranes coupled with a multiple-channel syringe pump. Based on membrane-based solid-phase extraction combined with UHPLC-MS/MS, a sensitive analytical method was established to determine six FWAs. The LODs was in range of 3-50 ng/L with the linear range of 0.02-100 μg/L. The developed method was used to quantify FWAs in bread wrapper and bread, and the spiked recoveries ranged from 78.1%-119% with RSD of 2.3%-9.7%. This work indicated that β-CD-CX4 POP was promising for the simultaneous recognition and adsorption of FWAs migrating from food contact materials.

Cyanobacteria and cyanotoxins in the environment and water intakes: Reports, diversity of congeners, detection by mass spectrometry and their impact on health

Cyanobacteria are aquatic microorganisms of high interest for research due to the production of secondary metabolites, among which the most popular are cyanotoxins, responsible for causing severe poisoning in humans and animals through ingestion or contact with contaminated water bodies. Monitoring the number of cyanobacteria in water and concentrations of secreted cyanotoxins with the aid of sensitive and reliable methods is considered the primary action for evaluating potentially toxic blooms. There is a great diversity of methods to detect and identify these types of micro contaminants in water, differing by the degree of sophistication and information provided. Mass Spectrometry stands out for its accuracy and sensitivity in identifying toxins, making it possible to identify and characterize toxins produced by individual species of cyanobacteria, in low quantities. In this review, we seek to update some information about cyanobacterial peptides, their effects on biological systems, and the importance of the main Mass Spectrometry methods used for detection, extraction, identification and monitoring of cyanotoxins.

The green synthesis of magnesium oxide nanocomposite-based solid phase for the extraction of arsenic, cadmium, and lead from drinking water

Solid-phase extraction (SPE) has attracted the attention of scientists because it can increase the selectivity and sensitivity measurements of analytes. Therefore, this study is designed to synthesise magnesium oxide nanoparticles (D-MgO-NPs) by an eco-friendly method using biogenic sources Duranta erecta followed by fabricating its chitosan-based polymeric composite (D-MgO-NC) for the SPE of heavy metals (HMs), i.e., arsenic (As), cadmium (Cd), and lead (Pb) from drinking water. Various analytical techniques were used for the surface characterization of D-MgO-NPs and D-MgO-NC. FTIR findings confirmed the formation of D-MgO-NC based on MgO association with the -OH/-NH2 of the chitosan. D-MgO-NC showed the smallest size of particles with rough surface morphology, followed by the crystalline cubic structure of MgO in its nanoparticle and composites. The synthesised D-MgO-NC was used as an adsorbent for the SPE of HMs from contaminated water, followed by their detection by atomic absorption spectrometry. Various experimental parameters, including pH, flow rate, the concentration of HMs, eluent composition, and volume, were optimised for the preconcentration of HMs. The limits of detection for As, Cd, and Pb of the proposed D-MgO-NC-based SPE method were found to be 0.008, 0.006, and 0.012 μm L-1, respectively. The proposed method has an enrichment factor and relative standard deviation of >200 and <5.0%, respectively. The synthesised D-MgO-NC-based SPE method was successfully applied for the quantitative detection of As, Cd, and Pb in groundwater samples, which were found in the range of 18.3 to 15.2, 3.20 to 2.49, and 8.20 to 6.40 μg L-1, respectively.

Highly sensitive detection of okadaic acid in seawater by magnetic solid-phase extraction based on low-cost metal/nitrogen-doped carbon nanotubes

Algae toxins pose a severe threat to human health all over the world. In this study, magnetic metal/nitrogen-doped carbon nanotubes (M-NCNTs) were facilely synthesized based on one-step carbonization and applied for magnetic solid-phase extraction of okadaic acid (OA) from seawater followed by high performance liquid chromatographic tandem mass spectrometry (HPLC-MS/MS) analyses. Differences in the physicochemical properties of the three prepared materials (Fe/Co/Ni-NCNTs) were investigated to confirm the best extraction material. Among them, Ni-NCNTs demonstrated a faster extraction rate (10 min) and higher adsorption capacity (223.5 mg g^-1), mainly due to the higher specific surface area, suitable pore structure and more abundant pyridine nitrogen ring. Under the optimal conditions, the calibration curve was linear over the range (1.0-800.0 pg mL^-1) with good determination coefficients (R) of 0.9992. The limit of detection (LOD) obtained in multiple replicates was 0.4 pg mL^-1. Three seawater samples were measured by the developed method, 12.3 pg mL^-1 of OA was detected with a satisfying recovery (88.6%-106.7%) and acceptable repeatability (RSD ≤ 4.8%, n = 6). The results demonstrate that M-NCNTs materials are a promising candidate for magnetic solid-phase extraction. Benefiting from its high extraction and interference resistance, the established analytical method is expected to be extended to detect other marine environmental pollutions.

Perfluoro octanoic acid-modified magnetic hyperbranched polyamideamine as a sorbent for the extraction of fluorine-containing pesticides from water samples

Perfluoro octanoic acid was modified on the surface of magnetic hyperbranched polyamideamine by acid amine condensation. The morphology and chemical composition of perfluoro octanoic acid-modified magnetic hyperbranched polyamideamine was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, zeta potential, particle size analysis, Brunauer-Emmett-Teller measurement, and X-ray photoelectron spectroscopy. Perfluoro octanoic acid-modified magnetic hyperbranched polyamideamine was applied in magnetic solid phase extraction for the separation and enrichment of four fluorine-containing pesticides (indoxacarb, metaflumizone, cyflumetofen, and cyhalothrin). The magnetic solid phase extraction method based on perfluoro octanoic acid-modified magnetic hyperbranched polyamideamine has low method detection limits (0.30-0.49 μg/L), a satisfactory coefficient of determination (0.9995-0.9999), wide linear ranges (2.5-250 μg/L), and good repeatability (intraday: 2.6-4.7%; interday: 1.1-7.9%). The enrichment factors and extraction efficiences varied from 55 to 76 and 69 to 96%, respectively. The sorbent-to-sorbent reproducibility was in the range of 3.2-7.6%, indicating that the synthesis of the sorbent was reliable. For the detection of actual water samples, the relative recoveries were in the range from 80.1 to 114.4% with relative standard deviations less than 9.6%. The calculation results of quantum chemistry calculations showed that after the modification of perfluoro octanoic acid, the interaction between the sorbent and four fluorine-containing pesticides was stronger.

Recent advances and applications of cyclodextrins in magnetic solid phase extraction

Cyclodextrins (CDs) as a family of cyclic oligosaccharides are toroidal with a hydrophobic interior and a hydrophilic exterior. They are well-known for their ability to form host-guest inclusion complexes with different compounds. They are used as chiral stationary phases in high performance liquid chromatography (HPLC) and gas chromatography (GC) or as chiral reagents in the background electrolyte of capillary electrophoresis (CE). In recent years, they have been used for modification of sorbents or as sorbents in solid phase extraction (SPE) procedures. Magnetic solid-phase extraction (MSPE), as a new type of SPE procedure, has received considerable attention due to its rapid phase separation process as compared to traditional extraction mode. This review covers the synthesis of CD-based magnetic sorbents (such as immobilization of CDs onto the different supports, production of nanosponges, and making hybrid substances with nanomaterials) and the use of these compounds in MSPE of different analytes from biological, environmental, and food samples. Also, prospects of CD-based sorbents for sample pre-treatment are also proposed.

Facile mechanochemistry synthesis of magnetic covalent organic framework composites for efficient extraction of microcystins in lake water samples

Easy-preparation magnetic solid-phase extraction (MSPE) adsorbents with excellent extraction performance are very indispensable for MSPE techniques. Herein, a magnetic carbon nanotube covalent organic framework composite (MCNTs@TpPa-1) was prepared simply and rapidly through mechanochemical synthesis as MSPE adsorbent for enriching microcystins (MCs). The synthesized MCNTs@TpPa-1 exhibited well water dispersibility, high affinity with MCs and large surface area, resulting in outstanding extraction performance for MCs. Subsequently, combined with high-performance liquid chromatography with tandem mass spectrometry (HPLC-MS/MS), an efficient, sensitive and convenient MSPE method was set up for the determination of trace MCs from aqueous sample, which exhibited acceptable repeatability (RSDs (relative standard deviations) ≤ 6.8%, n = 6), low limits of detection (LODs, 0.8-1.5 pg mL^-1), reliable linearity (R ≥ 0.9991) and broad range of linearity (2.0-1000 pg mL^-1). Furthermore, the developed method was applied to lake samples and trace MCs (9.6-24.6 pg mL^-1) were found with satisfactory recovery (85.0-106.0%). The results indicated powerfully MCNTs@TpPa-1 was of significant potential as an MSPE sorbent for detection of trace MCs in water. Moreover, considering the complexity of traditional preparation methods, novel prospects for preparing magnetic covalent organic frameworks (COFs) with excellent extraction properties were opened up.

High crystalline magnetic covalent organic framework with three-dimensional grapevine structure for ultrasensitive extraction of nitro-polycyclic aromatic hydrocarbons in food and environmental samples

Developing and establishing an efficient pre-treatment approach for the precise extraction of nitrated-polycyclic aromatic hydrocarbons (N-PAHs) from real-life samples is critical for ensuring their safety. In this study, a novel crystalline magnetic covalent organic framework with a grapevine structure not a single core-shell, Fe₃O₄@TAPT-DMTA-COF, was fabricated via chemical bonding. Unchanging the reticulated structure and high crystallinity of TAPT-DMTA-COF, the combination made this material possess not only simple operation via magnetic decantation but also remarkable chemical stability. Fe₃O₄@TAPT-DMTA-COF had a large surface area (1578.45 m²/g), and rich electronegative triazine-groups, which makes it become a superior magnetic enrichment material for trace N-PAHs. For N-PAHs analysis, low limits of detection (LODs) (1.43-17.24 ng/L), excellent relative standard deviations (RSDs ≤ 11.52%), and wide linearity (10-5000 ng/L) were obtained. Real-life applications based on this composite have been successfully explored by capturing the N-PAHs emitted from food and environmental samples.

Selection of Covalent Organic Framework Pore Functionalities for Differential Adsorption of Microcystin Toxin Analogues

Microcystins (MCs), produced by Microcystis sp, are the most commonly detected cyanotoxins in freshwater, and due to their toxicity, worldwide distribution, and persistence in water, an improvement in the monitoring programs for their early detection and removal from water is necessary. To this end, we investigate the performance of three covalent organic frameworks (COFs), TpBD-(CF₃)₂, TpBD-(NO₂)₂, and TpBD-(NH₂)₂, for the adsorption of the most common and/or toxic MC derivatives, MC-LR, MC-RR, MC-LA, and MC-YR, from water. While MC-LR and MC-YR can be efficiently adsorbed using all three COF derivatives, high adsorption efficiencies were found for the most lipophilic toxin, MC-LA, with TpBD-(NH₂)₂, and the most hydrophilic one, MC-RR, with TpBD-(NO₂). Theoretical calculations revealed that MC-LA and MC-RR have a tendency to be located mainly on the COF surface, interacting through hydrogen bonds with the amino and nitro functional groups of TpBD-(NH₂)₂ and TpBD-(NO₂)₂, respectively. TpBD-(NO₂)₂ outperforms the adsorbent materials reported for the capture of MC-RR, resulting in an increase in the maximum adsorption capacity by one order of magnitude. TpBD-(NH₂)₂ is reported as the first efficient adsorbent material for the capture of MC-LA. Large differences in desorption efficiencies were observed for the MCs with different COFs, highlighting the importance of COF-adsorbate interactions in the material recovery. Herein we show that efficient capture of these toxins from water can be achieved through the proper selection of the COF material. More importantly, this study demonstrates that by careful choice of COF functionalities, specific compounds can be targeted or excluded from a group of analogues, providing insight into the design of more efficient and selective adsorbent materials.

Application of magnetic nanomaterials in bioanalysis

The importance of magnetic nanomaterials and magnetic hybrid materials, which are classified as new generation materials, in analytical applications is increasingly understood, and research on the adaptation of these materials to analytical methods has gained momentum. Development of sample preparation techniques and sensor systems using magnetic nanomaterials for the analysis of inorganic, organic and biomolecules in biological samples, which are among the samples that analytical chemists work on most, are among the priority issues. Therefore in this review, we focused on the use of magnetic nanomaterials for the bioanalytical applications including inorganic and organic species and biomolecules in different biological samples such as primarily blood, serum, plasma, tissue extracts, urine and milk. We summarized recent progresses, prevailing techniques, applied formats, and future trends in sample preparation-analysis methods and sensors based on magnetic nanomaterials (Mag-NMs). First, we provided a brief introduction of magnetic nanomaterials, especially their magnetic properties that can be utilized for bioanalytical applications. Second, we discussed the synthesis of these Mag-NMs. Third, we reviewed recent advances in bioanalytical applications of the Mag-NMs in different formats. Finally, recently literature studies on the relevance of Mag-NMs for bioanalysis applications were presented.

Cyanuric chloride-imidazole dendrimer functionalized nanoparticles as an adsorbent for magnetic solid phase extraction of quaternary ammonium compounds from fruit and vegetable puree based infant foods

A novel magnetic solid-phase extraction (MSPE) material (Fe₃O₄@SiO₂-NH₂-G2) had been prepared and employed for adsorption and analysis of seven quaternary ammonium compounds (QACs) in infant fruit and vegetable products coupled with high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). In this paper, Fe₃O₄@SiO₂-NH₂-G2 was synthesized based on Fe₃O₄@SiO₂-NH₂ and dendrimer (G2) consisting of cyanuric chloride and imidazole. The morphology, configuration and magnetic behavior of the magnetic material were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FT-IR), X-ray diffraction (XRD), and vibrating sample magnetometer (VSM). Critical parameters affecting extraction efficiency, such as the adsorbent amount, sample pH, extraction time, the type of eluent, and desorption time, were optimized. The proposed method provided good linearity with the correlation coefficients (R²) of 0.9992-0.9999, low limits of detection (LODs) (0.05-0.50 μg kg^-1) and limits of quantitation (LOQs) (0.20-2.00 μg kg^-1). The satisfactory method recoveries in three spiked infant fruit and vegetable products samples were between 80.12% and 101.35% with the relative standard deviations (RSDs) less than 12.04%. In summary, the established method was an effective sample preparation method and showed good prospect for the analysis of QACs in complex matrices.

A Mini-Review on Detection Methods of Microcystins

Cyanobacterial harmful algal blooms (CyanoHABs) produce microcystins (MCs) which are associated with animal and human hepatotoxicity. Over 270 variants of MC exist. MCs have been continually studied due of their toxic consequences. Monitoring water quality to assess the presence of MCs is of utmost importance although it is often difficult because CyanoHABs may generate multiple MC variants, and their low concentration in water. To effectively manage and control these toxins and prevent their health risks, sensitive, fast, and reliable methods capable of detecting MCs are required. This paper aims to review the three main analytical methods used to detect MCs ranging from biological (mouse bioassay), biochemical (protein phosphatase inhibition assay and enzyme linked immunosorbent assay), and chemical (high performance liquid chromatography, liquid chromatography-mass spectrometry, high performance capillary electrophoresis, and gas chromatography), as well as the newly emerging biosensor methods. In addition, the current state of these methods regarding their novel development and usage, as well as merits and limitations are presented. Finally, this paper also provides recommendations and future research directions towards method application and improvement.

A fish scale-like magnetic nanomaterial as a highly efficient sorbent for monitoring the changes in auxin levels under cadmium stress

Sorbents with high surface utilization and good dispersibility are of great importance for the extraction performance of magnetic solid-phase extraction (MSPE). In this study, a fish scale-like magnetic nanomaterial (Co@Co3O4/OCN) was synthesized, which can be used as a highly efficient MSPE sorbent due to its strong magnetism, special morphology, doping of N element, numerous micro-mesopore cavities and organic functional groups (hydroxyl and carboxyl). Furthermore, a Co@Co3O4/OCN-based MSPE method for monitoring the changes in the levels of three auxins (indole-3-acetic acid, indole-3-propionic acid and 3-indole butyric acid) was successfully established. Wide linear ranges (1.0-1000.0 pg mL-1) with good correlation coefficients (R > 0.9992), low limits of detection (LODs, 0.2-4.0 pg mL-1) and satisfactory repeatability (RSD ≤5.9%, n = 3) were obtained. Using the developed method, various growth parts and different growth periods of plants under Cd stress were monitored. The results showed that auxins in various parts of plants showed differential response under Cd stress, and there was a threshold for the changes in auxin levels against Cd stress. This indicates that the developed fish scale-like Co@Co3O4/OCN nanomaterial has a good application prospect for enriching small molecular targets containing hydroxyl and carboxyl groups.

Magnetic solid-phase extraction as a novel method for the prediction of the bioaccessibility of polycyclic aromatic hydrocarbons

Chemical methods used to predict the bioaccessibility of hydrophobic organic compounds (HOCs) still need further development and improvement. In this work, magnetic solid-phase extraction (MSPE) based on poly(β-cyclodextrin)-coated magnetic polydopamine (Fe₃O₄@PDA@PCD) was first introduced to assess the bioaccessibility of polycyclic aromatic hydrocarbons (PAHs) in soils. Due to its good hydrophilicity and submicrometer scale, Fe₃O₄@PDA@PCD displayed a higher extraction rate for PAHs in an aqueous solution (equilibrium time < 5 min) than Tenax resin, which had an equilibrium time longer than 30 min. The merits of Fe₃O₄@PDA@PCD are beneficial to accelerate the desorption of PAHs from soil, especially for high molecular weight PAHs, in which the amounts extracted by Fe₃O₄@PDA@PCD were 1.2-2.8 times higher than those extracted by Tenax resin. The desorption kinetics data were well fitted with a two- or three-fraction model. The fitting results indicated that the MSPE method can be used to predict the bioaccessible fractions of PAHs. By comparing the prediction results obtained from the MSPE method with bioassays using earthworms, a significant linear correlation (R² = 0.98) with a slope statistically close to 1 was obtained. These results suggested that the MSPE method can act as a simple and efficient method to measure the bioaccessibility of PAHs in soil.

Simultaneous Pre-Concentration and HPLC-MS/MS Quantification of Phycotoxins and Cyanotoxins in Inland and Coastal Waters

The purpose of this study was to set up a sensitive method for the simultaneous determination of phycotoxins and cyanotoxins-Emerging pollutants with different structures and harmful properties (hepatotoxicity, neurotoxicity and cytotoxicity)-In environmental waters. Due to the low concentrations detected in these samples, a pre-concentration step is required and here it was performed in a single step with a commercial cartridge (Strata™-X), achieving enrichment factors up to 200 and satisfactory recovery (R = 70-118%) in different aqueous matrices. After solid-phase extraction (SPE), toxins were separated and quantified by High Performance Liquid Chromatography- Heated ElectroSpray Ionisation Tandem Mass Spectrometry (HPLC-HESI-MS/MS) in Multiple Reaction Monitoring (MRM) mode. An analytical evaluation of the proposed method was done based on the analytical figures of merit, such as precision and trueness, linearity, selectivity, and sensitivity, and it turned out to be a robust tool for the quantification of ng L^-1 levels, phycotoxins and cyanotoxins in both freshwater and saltwater samples.

Magnetic C60 nanospheres based solid-phase extraction coupled with isotope dilution gas chromatography-mass spectrometry method for the determination of sixteen polycyclic aromatic hydrocarbons in Chinese herbal medicines

C₆₀-based magnetic nanospheres were synthesized by coating Fe₃O₄ nanospheres with silica, then modifying with 3-aminopropyltriethoxysilane as a linker and a C₆₀ fullerene stationary phase. The morphologies, magnetic properties, infrared absorption and carbon content of magnetic nanospheres were studied by TEM, VSM, FTIR and carbon and sulfur analyzer. The magnetic nanospheres were employed for the magnetic solid-phase extraction (MSPE) of 16 polycyclic aromatic hydrocarbons (PAHs) in nine Chinese herbal medicines. The analyses were conducted by isotope dilution gas chromatography-mass spectrometry. The main parameters influencing the extraction, including extraction solvent, adsorbent amount, and extraction time were optimized. Method validation showed that the limit of detection (LOD) was 0.02-0.11 µg/kg, and the limit of quantification (LOQ) was 0.07-0.36 µg/kg. The spiked recoveries rates for 16 PAHs in white peony root were 84.7-107.2%. The relative standard deviation (RSD) was 1.7-8.4%. The established method was further used for the determination 16 PAHs in nine Chinese herbal medicines. Total content of 16 PAHs varied from 73.6 µg/kg (fructus lycii) to 2172.6 µg/kg (astragalus root). The results indicate that the pollution of PAHs in Chinese herbal medicines is serious. The established method can effective detect PAHs contamination in Chinese herbal medicines.

Simultaneous enrichment and determination of cadmium and mercury ions using magnetic PAMAM dendrimers as the adsorbents for magnetic solid phase extraction coupled with high performance liquid chromatography

In present study, a sensitive and efficient method based on magnetic PAMAM dendrimers as the sorbents for magnetic solid-phase extraction (MSPE) coupled with high performance liquid-phase chromatography and ultraviolet variable wavelength detector (HPLC-VWD) was developed for simultaneous determination of trace cadmium and mercury ions. Sodium diethyldithiocarbamate (DDTC-Na) was used as the chelating agent during the elution process. Parameters that would affect the extraction efficiency including PAMAM generation, adsorbent dosage, adsorption time, elution time and volume, pH and coexisting ions were investigated to achieve the best adsorption efficiency. Under the optimal conditions, good linear relationship was obtained in the range of 0.05-200 μg L^-1 for Cd²⁺ and 0.1-200 μg L^-1 for Hg²⁺, and the limits of detection were 0.016 and 0.040 μg L^-1, respectively. The spiked recoveries of Cd²⁺ and Hg²⁺ were satisfied in the range of 91.5-105% (n = 3). The proposed method was proved to be an alternative and reliable method to determine trace Cd²⁺ and Hg²⁺ in water samples.

The classification and application of cyclodextrin polymers: a review

After introducing the concept of cyclodextrin polymers, their classification and applications have been summarized.

Cyclodextrin-based sorbents for solid phase extraction

Cyclodestrins (CDs) are cyclic oligosaccharides well-known for their ability to form host-guest inclusion complexes with properly sized compounds. They have been used for decades as chiral selectors as well as drug delivery systems within the frameworks of separation science and pharmaceutical science. More recently, their use has been extended to the field of extractive science under the stimulus of additional advantageous characteristics, such as low-price, negligible environmental impact, non-toxicity, as arising from the fact that natural CDs are starch degradation products. To abate their solubility in water and generate novel sorbents for solid phase extraction, the following approaches have been employed: (i) immobilization onto inert materials (silica, attapulgite, etc.); (ii) immobilization onto nanomaterials (magnetic nanoparticles, titanium oxide, carbon nanotubes, graphene oxide, etc.); (iii) polymerisation with specific cross-linkers to form the so-called CD-based nanosponges. Particularly promising are these last ones for their selectivity, mesoporous structure, insolubility in aqueous media and good dispersibility. This review offers a concise overview on the state of art and future prospects of CDs in this important sector of the analytical chemistry, offering a critical perspective of the most significant applications.

Determination of microcystins in water samples by deep eutectic solvent-based vortex-assisted liquid–liquid microextraction coupled with ultrahigh-performance liquid chromatography-high resolution mass spectrometry

An eco-friendly and efficient DES-based VALLME coupled UHPLC-ESI(+)-qTOF-MS method was developed to determine MC-YR and MC-LR in surface water samples.