The recent advances in magnetic sorbents and their applications

Smart photo-driven composite system containing thermosensitive P(NIPAM-NVK) and photoactive PANI for the rapid removal of anionic dyes

A smart composite system based on thermosensitive polymers and photosensitive polyaniline (PANI) was constructed in this work, enabling efficient photo-driven adsorption and separation of anionic dyes within a short time. Thermosensitive copolymers (P(NIPAM-NVK)) of N-isopropylacrylamide (NIPAM) and N-vinylcarbazole (NVK) with adjustable low critical solution temperatures (LCST) were synthesized via a free radical copolymerization method. PANI was then composited with P(NIPAM-NVK) as a photothermal agent and dye adsorbent. The developed P(NIPAM-NVK)/PANI composite systems showed a rapid temperature increase under visible light irradiation, triggering the transition of P(NIPAM-NVK) from the sol state to a bulk gel state. Simultaneously, PANI and Congo Red (CR) anionic dye were efficiently encapsulated within the gel state of P(NIPAM-NVK) via intermolecular interactions, facilitating the rapid separation of aqueous CR through a direct solid-liquid process to yield clean water. The P(NIPAM-NVK10)/PANI0.5 composite system afforded a removal efficiency > 98 % for CR (80 mg/L) within 5 min under visible light illumination. These findings hold great promise for the eco-friendly treatment of dye-containing wastewater.

Ultrasound-assisted continuous flow synthesis of natural phenolic-coated Fe3O4 for magnetic solid phase extraction of tetracycline residues in honey

Waste rubber bark abundant in phenolics can be used to produce an adsorbent for the enrichment and determination of tetracycline. Fe3O4 magnetic nanoparticles (Fe3O4 MNPs) coated with naturally extracted phenolics from waste rubber bark were synthesized for the first time by ultrasound combined with a continuous flow approach. The production of Fe3O4 MNPs with effective contact surface areas (45.3 m2 g-1) was employed as a novel attractive sorbent in magnetic solid phase extraction (MSPE) to selectively preconcentrate oxytetracycline, tetracycline, chlortetracycline, and doxycycline before HPLC-UV analysis. This MSPE-HPLC exhibited wide linear ranges (14.0-260.0 μg kg-1), with low limits of detection (10.0 μg kg-1) and quantitation (14.0-20.0 μg kg-1), and was successfully applied to quantify tetracycline residues in honey samples, with recoveries ranging from 81.3 % to 117.9 %. This method offers a potential alternative for determining tetracycline in food with a high enrichment factor, high precision, and more effective accuracy, selectivity, and sensitivity.

Nanomaterial-based magnetic solid-phase extraction in pharmaceutical and biomedical analysis

Magnetic solid-phase extraction (MSPE) holds significant scientific and technological interest as a novel sample preparation method for complex samples due to its easy operation, swift separation, high adsorption efficiency, and environmental friendliness. As the core of MSPE, magnetic sorbents have captured tremendous attention in recent years. Various promising nanomaterials, such as metal-organic frameworks and covalent organic frameworks, have been synthesized and utilized as sorbents in pharmaceutical and biomedical analysis. This review intends to (1) summarize recent progress of magnetic sorbents applied in this area and discuss their advantages, disadvantages, possible interaction mechanisms with the target substances; (2) explore their innovative applications in the analysis of pharmaceuticals, proteins, peptides, nucleic acids, nucleosides, metabolites, and other disease biomarkers from 2021 to 2024; (3) present the integration of MSPE with emerging analytical technologies; and (4) discuss the current challenges and future perspectives. It is expected to provide references and insights for the development of novel magnetic sorbents and their applications in bioanalysis.

Recent advancements in the extraction and analysis of phthalate acid esters in food samples

Phthalate acid esters (PAEs) are ubiquitous environmental pollutants present in food samples, necessitating accurate detection for risk assessment and remediation efforts. This review provides an updated overview of the recent progress on the PAEs analysis regarding sample pretreatment techniques and analytical methodologies over the latest decade. Advances in sample preparation include solid-based extraction techniques replacing conventional liquid-liquid extraction, with solid sorbents emerging as promising alternatives due to their minimal solvent consumption and enhanced selectivity. Although techniques like the microextraction methods offer versatility and reduced solvent reliance, there is a need for more efficient and environmentally friendly techniques enabling on-site portable detection. High-resolution mass spectrometry is increasingly utilized for its enhanced sensitivity and reduced contamination risks. However, challenges persist in developing in situ analytical techniques for trace PAEs in complex food samples. Future research should prioritize novel analytical techniques with superior sensitivity and selectivity, addressing current limitations to meet the demand for precise PAEs detection in diverse food matrices.

Metal-organic framework functionalized magnetic Nb2CTX for high enrichment of polychlorinated biphenyls in water prior to gas chromatography tandem mass spectrometry

As a typical kind of persistent organic pollutants, polychlorinated biphenyls (PCBs) may cause great harm to human health. Recently, MXene has gained considerable attention due to its specific properties for the removal of pollutants by various principles. Present work reported a new functionalized MXene material, NH2-MIL-88 modified magnetic Nb2CTX, for developing a facile and efficient magnetic solid phase extraction method for enrichment and sensitive detection of PCBs in environmental water samples. The adsorption mechanism and parameters that may impact the extraction efficiencies of PCBs were explored. Gas chromatography-tandem mass spectrometry was utilized to detect the enriched PCBs. The results demonstrated that nine PCBs possessed good linearities in the range of 0.005 ∼ 50 μg L-1 and 0.005∼ 40 μg L-1, respectively. The detection limits of PCBs were over range of 0.06 - 0.28 ng L-1. The adsorption of PCBs on NH2-MIL-88 modified magnetic Nb2CTX followed quasi-second-order kinetic and Langmuir adsorption isotherm models. The fortified recoveries in real water samples ranged from 87.6 % to103.4 % (n = 3), which confirmed that the established method owned merits such as simplicity, rapidness, robustness, and high extraction efficiencies, and might be utilized for the detection of trace PCBs in environmental water samples.

Preparation of a sustainable magnetic sorbent for the extraction and preconcentration of progestogens in natural water samples

A film composed of agarose and graphene (G) and magnetic nanoparticles (G-MNPs) is proposed as a sorbent for the extraction and determination of medroxyprogesterone (MED), levonorgestrel (LEV), norethisterone (NOR) and progesterone (PRO) in natural water samples. Both the preparation of the film and the extraction procedure were optimized. The optimal extraction parameters were as follows: isopropyl alcohol as activation solvent, sample pH value of 3.0, extraction time of 30 min, 1.00 mL of acetonitrile as eluent, elution time of 5 min and sample volume of 100.00 mL. HPLC with photodiode array detector was used for the separation and determination. The method presented a linear range between 2.50 and 75.0 μg L-1 for all analytes, and the LODs were between 1.40 and 1.80 μg L-1. The method was applied to natural water samples, obtaining satisfactory recovery values (75-111 %). In conclusion, for the immobilization of the G-MNPs, agarose was used, which is a non-toxic, renewable and biodegradable material. The G-MNPs-agarose film was reused up to 70 times, without losing its extraction capacity significantly and presenting excellent sorbent properties, which allow the extraction and preconcentration of the progestogens under study.

Advances and Applications of Hybrid Graphene-Based Materials as Sorbents for Solid Phase Microextraction Techniques

The advancement of traditional sample preparation techniques has brought about miniaturization systems designed to scale down conventional methods and advocate for environmentally friendly analytical approaches. Although often referred to as green analytical strategies, the effectiveness of these methods is intricately linked to the properties of the sorbent utilized. Moreover, to fully embrace implementing these methods, it is crucial to innovate and develop new sorbent or solid phases that enhance the adaptability of miniaturized techniques across various matrices and analytes. Graphene-based materials exhibit remarkable versatility and modification potential, making them ideal sorbents for miniaturized strategies due to their high surface area and functional groups. Their notable adsorption capability and alignment with green synthesis approaches, such as bio-based graphene materials, enable the use of less sorbent and the creation of biodegradable materials, enhancing their eco-friendly aspects towards green analytical practices. Therefore, this study provides an overview of different types of hybrid graphene-based materials as well as their applications in crucial miniaturized techniques, focusing on offline methodologies such as stir bar sorptive extraction (SBSE), microextraction by packed sorbent (MEPS), pipette-tip solid-phase extraction (PT-SPE), disposable pipette extraction (DPX), dispersive micro-solid-phase extraction (d-µ-SPE), and magnetic solid-phase extraction (MSPE).

Preparation of Monolith for Online Extraction and LC-MS Analysis of β-Estradiol in Serum Via a Simple Multicomponent Reaction

Multicomponent reactions offer efficient and environmentally friendly strategies for preparing monoliths suitable for applications in analytical chemistry. In the described study, a multicomponent reaction was utilized for the one-pot miniaturized preparation of a poly(propargyl amine) polymer inside commercial silica-lined PEEK tubing. The reaction involved only small amounts of reagents and was characterized by atom economy. The resulting monolithic column was incorporated into an autosampler system for the online extraction and cleanup of β-estradiol from human serum. Sample pretreatment was simplified to a simple dilution with methanol and centrifugation to remove proteins. The resulting platform included LC-MS analysis in multiple reaction monitoring for quantitative analysis of β-estradiol. The method was validated in serum, demonstrating practical applicability for the monitoring of fertile women. Recoveries were above 94%, and LOD and LOQ values at 0.008 and 0.18 ng mL-1, respectively. The developed platform proved to be competitive with previous methods for solid-phase microextraction of β-estradiol in serum, with comparable recovery and sensitivity but with the advantage of nearly complete automation. The environmental impact of the process was evaluated as acceptable due to the miniaturization of the monolith synthesis and the automation of extraction. The drawback associated with the LC-MS technique can be reduced by the inclusion of additional analytes in a single investigation. The work demonstrates that multicomponent reactions are versatile, economical, and possibly a green methodology for producing reversed-phase and mixed-mode sorbents, enabling miniaturization of the entire analytical procedure from the preparation of extraction sorbents to analysis.

A miniaturized stir bar sorptive dispersive microextraction method for the determination of bisphenols in follicular fluid using a magnetic covalent organic framework

BACKGROUND

Bisphenols, particularly bisphenol A (BPA), are the primary monomers used as additives in the manufacturing of many consumer products. The exposure to these compounds is related to endocrine-disrupting and reproductive effects, among others. For this reason, the development of analytical methods for their determination in biological matrixes is needed to monitor the population exposure to these compounds. Their quantification at ovarian level (i.e., follicular fluid) is interesting for the assessment of the bisphenol content to draw conclusions about infertility problems. However, the background does not meet all requirements by focusing mainly on BPA.

RESULTS

In this work, a miniaturized stir bar sorptive dispersive microextraction (mSBSDME) approach has been developed for the determination of BPA and eight analogues in follicular fluid. In the proposed method, the sample is previously cleaned-up using a zirconia-based solid-phase extraction cartridge, removing proteins and phospholipids, and then subjected to the mSBSDME for the preconcentration of the analytes. For this purpose, a magnetic covalent organic framework was used as sorbent. A Plackett-Burman design was applied to select the significant variables affecting the mSBSDME. Afterwards, the only significant variable (i.e., sorbent amount) was optimized. Under the optimized conditions, the proposed method was properly validated, and satisfactory analytical parameters in terms of linearity (up to 50 ng mL-1), enrichment factors (8.5-14.3), limits of detection in the low ng mL-1 range, and precision (relative standard deviations below 11.5 %) were obtained. Finally, the method was successfully applied to five samples, detecting BPA and other two analogues.

SIGNIFICANCE

This method expands the potential applicability of the mSBSDME to other low-availability complex matrixes, which would otherwise be difficult to analyze. Moreover, it offers a valuable tool for monitoring the female population's exposure to bisphenols with the final aim of evaluating if infertility problems of women might be associated to the exposure to these highly endocrine disrupting compounds.

Deep eutectic solvents in sample preparation and determination methods of pesticides: Recent advances and future prospects

This review summarizes recent advances of deep eutectic solvents (DESs) in sample preparation and determination methods of pesticides in food, environmental, and biological matrices since 2019. Emphasis is placed on new DES categories and emerging microextraction techniques. The former incorporate hydrophobic deep eutectic solvents, magnetic deep eutectic solvents, and responsive switchable deep eutectic solvents, while the latter mainly include dispersive liquid-liquid microextraction, liquid-liquid microextraction based on in-situ formation/decomposition of DESs, single drop microextraction, hollow fiber-liquid phase microextraction, and solid-phase microextraction. The principles, applications, advantages, and limitations of these microextraction techniques are presented. Besides, the use of DESs in chromatographic separation, electrochemical biosensors, fluorescent sensors, and surface-enhanced Raman spectroscopy are discussed. This review is expected to provide a valuable reference for extracting and detecting pesticides or other hazardous contaminants in the future.

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 0.052-0.093 μg/L and 0.11-0.31 μg/L, respectively. Satisfactory relative recoveries of all carbamates were achieved from fortified water samples in the range of 93.89-101.01%.

An overview on human exposure, toxicity, solid-phase microextraction and adsorptive removal of perfluoroalkyl carboxylic acids (PFCAs) from water matrices

Perfluoroalkyl carboxylic acids (PFCAs) are sub-class of perfluoroalkyl substances commonly detected in water matrices. They are persistent in the environment, hence highly toxic to living organisms. Their occurrence at trace amount, complex nature and prone to matrix interference make their extraction and detection a challenge. This study consolidates current advancements in solid-phase extraction (SPE) techniques for the trace-level analysis of PFCAs from water matrices. The advantages of the methods in terms of ease of applications, low-cost, robustness, low solvents consumption, high pre-concentration factors, better extraction efficiency, good selectivity and recovery of the analytes have been emphasized. The article also demonstrated effectiveness of some porous materials for the adsorptive removal of the PFCAs from the water matrices. Mechanisms of the SPE/adsorption techniques have been discussed. The success and limitations of the processes have been elucidated.

Isolation of organophosphate pesticides from water using gold nanoparticles doped magnetic three-dimensional graphene oxide

Pesticides are a large group of pristine organic contaminants, which are widely discharged into environmental water due to agricultural activities. Hence, extraction, determination, and removal of pesticides from water resources are necessary for human health. In this study, novel adsorbent was developed based on three-dimensional magnetic graphene coated with gold nanoparticles (3D-MG@AuNPs) for extraction of chlorpyrifos, dicrotophos, fenitrothion, and piperophos as four specific organophosphorus pesticides (OPPs) from wastewater and tap water samples. The proposed nanocomposite was characterized; FTIR and EDX are performed for the expected functional groups and elemental analysis, SEM showed the unique and spherical AuNPs are well dispersed over graphene sheets. In this investigation, the important parameters that have effect on the extraction efficiency, including the desorbing solvent, desorbing solvent volume, vortex time, the extraction time, adsorbent dosage, pH of sample solutions, and salt effect were evaluated. In conclusion, the measured amounts of the chosen OPPs were determined using the gas chromatography microelectron capture (μECD-GC) method. Limits of quantification (S/N ratio of 10) and detection (S/N ratio of 3) were attained at concentrations of 0.26-0.43 μg.L^-1 and 0.08-0.14 μg.L^-1, respectively. According to the results of the investigations, the synthesized 3D-MG@AuNPs did not require any complicated sample preparation methods; therefore, it is a very good choice for solid magnetic phase extraction studies.

Analytical perspective and environmental remediation potentials of magnetic composite nanosorbents

The synthesis and application of magnetic nanosorbents to remove emerging pollutants have been considered the best environmental remediation and sustainability option. Incorporating magnetism shortens the treatment time and allows the sorbent to be recovered quickly using external magnetic with many cycles. The implementation of magnetic solid-phase extraction (MSPE) using magnetic materials of different shapes, sizes, and surface morphology can be a valuable tool in applying materials to prepare analytical samples. In MSPE applications, materials with strong magnetic domain can be used as precursors for constructing magnetic composite as a promising sorbent. This article focuses on the most recent and exceptional applications of magnetic adsorbents for preconcentration and removal purposes. Magnetic adsorbents, such as nanoparticles (NPs), foam, sponges, nanocomposites, hydrogels, and beads with multifunctional attributes have been comprehensively studied in terms of preparation procedures, limitations, advantages, and interactions between pollutants and magnetic composites. The role of magnetic sorbents in sample preparation methods, such as simple solid-phase extraction and microextraction, as well as sorptive extraction using a stir bar, was also examined. The use of magnetic adsorbents with analytical techniques, such as solid-phase extraction and solid-phase microextraction improves the method for preparing samples concerning the influential role of magnetic adsorbents. Towards the end, promising features and future outlook are also directed.

Magnetic covalent-organic frameworks-based extraction followed by UHPLC-MS/MS for determination and pharmacokinetic study of trace angoroside C in rat plasma after oral administration of Xuanbo Shuangsheng Granule

The composition of the traditional Chinese medicine compound preparation is complex, while the content of each active ingredient is extremely low, which brings difficulties to the plasma concentration detection. In this study, the magnetic covalent-organic frameworks were synthesized by a simple one-step Schiff base reaction and applied for the specific extraction of trace angoroside C in rat plasma prior to ultra-high-performance liquid chromatography-tandem mass spectrometry detection. The synthesized magnetic covalent-organic frameworks have high magnetic responsiveness (35.67 emu·g^-1 ), large surface area (110.9 m² ·g^-1 ), and strong stability. The as-prepared material can quickly extract angoroside C from plasma with high extraction efficiency, be easily separated with a magnet afterward, and can be reused for at least five times. The established method was systematically validated showing good linearity (0.1-5 ng·ml^-1 ), low limit of quantification (0.1 ng·ml^-1 ), good accuracy (93.18%-105.36%), and good precision (percentage relative standard deviation 3.60%-10.90%). Finally, the method was used to the pharmacokinetic study of trace angoroside C in rats after oral administration of Xuanbo Shuangsheng Granule.

Immobilization of Interfacial Activated Candida rugosa Lipase Onto Magnetic Chitosan Using Dialdehyde Cellulose as Cross-Linking Agent

Candidarugosa lipase (CRL) was activated with surfactants (sodium dodecyl sulfate [SDS]) and covalently immobilized onto a nanocomposite (Fe₃O₄-CS-DAC) fabricated by combining magnetic nanoparticles Fe₃O₄ with chitosan (CS) using polysaccharide macromolecule dialdehyde cellulose (DAC) as the cross-linking agent. Fourier transform infrared spectroscopy, transmission electron microscope, thermogravimetric analysis, and X-ray diffraction characterizations confirmed that the organic–inorganic nanocomposite support modified by DAC was successfully prepared. Enzymology experiments confirmed that high enzyme loading (60.9 mg/g) and 1.7 times specific enzyme activity could be obtained under the optimal immobilization conditions. The stability and reusability of immobilized CRL (Fe₃O₄-CS-DAC-SDS-CRL) were significantly improved simultaneously. Circular dichroism analysis revealed that the active conformation of immobilized CRL was maintained well. Results demonstrated that the inorganic–organic nanocomposite modified by carbohydrate polymer derivatives could be used as an ideal support for enzyme immobilization.

An efficient 3D adsorbent foam based on graphene oxide/AgO nanoparticles for rapid vortex-assisted floating solid phase extraction of bisphenol A in canned food products

In this study, a three-dimensional adsorbent was developed based on graphene oxide/AgO nanoparticles over interconnected nickel foam (GO/AgO@Ni foam) for rapid and efficient vortex assisted floating solid phase extraction of bisphenol A in canned food products prior to high performance liquid chromatography with a fluorescence detector. The analytical techniques scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared (FT-IR) were used for characterization of the synthetized GO/AgO@Ni foam. The effect of proficiency factors including pH, foam size, vortexing time, salt addition, sample volume, desorption type and volume, and desorption time on the extraction efficiency of bisphenol A were explored through the matrix match method. Under the above experimental conditions, the figures of merit of the method were acquired as LODs (S/N = 3) of 0.18-0.84 μg kg^-1, LOQs of 0.61-2.81 μg kg^-1 (S/N = 10), linear ranges of 0.5-500 μg kg^-1, and enrichment factors of 235.5-244.9. The inter-day precision values (RSD%, n = 7) of 2.5-3.6 and the intra-day precision (%) of (5 days and seven replicates for each day) 2.8-3.8 were achieved for bisphenol A at a concentration of 50 μg kg^-1. The relative recoveries of 94.0% to 99.6% were obtained for the canned food samples.

Heterogeneous adsorbent based on CeZrO2 nanoparticles doped magnetic graphene oxide used for vortex assisted magnetic dispersive solid phase extraction of erythromycin in chicken

A simple, fast, and efficient method of vortex assisted magnetic dispersive solid phase extraction for separation and pre-concentration of erythromycin in chicken samples prior to high LC-UV determination has been developed. The novel heterogeneous CeZrO₂ nanoparticles doped magnetic graphene oxide, for use as an efficient nanosorbent, was synthetised and applied for the adsorption of erythromycin. The synthetised nanosorbent was characterised using both Fourier-transform infra-red (FT-IR) and energy dispersive X-Ray (EDX) spectroscopy together with field emission scanning electron microscopy-EDX. To obtain the best extraction condition and maximum extraction efficiency of erythromycin, the effect of important parameters including pH, amount of sorbent, vortexing time, ionic strength, sample volume, and desorption conditions were investigated. At optimum conditions, a linear range of 0.25-300 µg kg^-1, LOD (S/N = 3) of 0.079 µg kg^-1, and LOQ (S/N = 10) of 0.270 µg kg^-1 were obtained. The precision of the method was established as having an RSD (%) at 100 µg kg^-1 of erythromycin for seven replicates of 2.6% and 3.2% for the intra-day and the inter-day, respectively. Recoveries over 94.0% confirmed a high capability of the proposed method for separation and determination of erythromycin residues in chicken being one of the most important animal products.

Ultrasound-assisted dispersive magnetic solid-phase extraction of cadmium, lead and copper ions from water and fruit juice samples using DABCO-based poly (ionic liquid) functionalized magnetic nanoparticles

A poly (ionic liquid) (PIL) functionalized magnetic nanoparticles methodology was developed and utilized as an efficient adsorbent for the simultaneous extraction of cadmium, lead, and copper ions from water and fruit juice samples. The novel adsorbent was fabricated by grafting DABCO-based PIL onto silica-coated Fe₃O₄ nanoparticles via copper (0)-mediated reversible-deactivation radical polymerization. Different techniques properly characterized the developed nanoparticles. The central composite design was used to analyze the simultaneous effects of various parameters on the extraction efficiency. The detection limits for water samples ranged between 3.2 and 9.2 ng.L^-1, and fruit juice samples varied from 0.0103 to 0.1082 μg.kg^-1. The recovery ranged from 94.1 to 101.3% and 93.6 to 105.1% for water and fruit juice samples, respectively. The relive measurement uncertainty ranged from 7.7 to 13.6%. The proposed method is rapid, sensitive, environmentally friendly, and useful for monitoring the residues of heavy metal ions in water and fruit juice samples.

Monodispersed CaCO3@hydroxyapatite/magnetite microspheres for efficient and selective extraction of benzoylurea insecticides in tea beverages samples

A novel monodispersed CaCO₃@hydroxyapatite/magnetite microsphere (CaCO₃ @HAP/Fe₃O₄) was prepared via an in-situ growth strategy, and applied as an adsorbent for efficient and selective adsorption of benzoylurea insecticides (BUs) in various tea beverages samples. The sorbent exhibited uniformity in particle size, good mono-dispersibility and excellent solvent stability. The adsorption equilibrium of BUs (100 ng/mL) in 10 mL of tea beverages samples was achieved on 20 mg of CaCO₃ @HAP/Fe₃O₄ within 10 min. The adsorption followed pseudo-second-order kinetics and Langmuir models and the maximum adsorption capacities of 131.9-161.3 mg/g were accomplished via hydrophobic interactions, hydrogen bonding, and the affinity of F atom and Ca²⁺. Coupled with high performance liquid chromatography, the method offered wide linear ranges of 0.8-1000 ng/mL with correlation coefficients (r) ≥ 0.9995, low limits of detection of 0.2-0.3 ng/mL and large enrichment factors of 75.7-102. The recoveries ranged from 75.7%- 102% with intra- and inter-day precisions of 1.9%- 9.3% and 1.6%- 11.8%, respectively. In addition, CaCO₃ @HAP/Fe₃O₄ could be easily regenerated and reused at least 10 times with no significant loss of recovery. These results revealed an alternative strategy for fast and convenient determination of BUs in tea beverages samples and proved the great feasibility of CaCO₃ @HAP/Fe₃O₄ in the application for the selective adsorption of BUs.

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

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

Graphene oxide modified magnetic polyamidoamide dendrimers based magnetic solid phase extraction for sensitive measurement of polycyclic aromatic hydrocarbons

In this study, graphene oxide modified magnetic polyamidoamine dendrimers (MNPs@PAMAM-G2.0@GO) nanoparticles were successfully prepared by amidation method. The obtained MNPs@PAMAM-G2.0@GO nanocomposites were examined by fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscope (SEM) and transmission electron microscopy (TEM), etc. MNPs@PAMAM-G2.0@GO exhibited excellent adsorption property and was investigated for magnetic solid phase extraction (MSPE) of polycyclic aromatic hydrocarbons (PAHs) from water. The detection of extracted PAHs was accomplished by high performance liquid chromatography (HPLC) and gas chromatography tandem mass spectrometry (GC-MS/MS). The target PAHs included anthracene (ANT), pyrene (PYR), fluoranthene (FLT), carbazole (CB), 7-methylquinoline (7-MQL), 9-methylcarbazole (9-MCB), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DBT). Important operation parameters for MSPE that could affect the extraction efficiencies of PAHs were investigated in detail. Under optimal parameters, the constructed method demonstrated excellent linear range with 0.001-10 μg L^-1 for analytes and low limits of detection within the range of 0.11-0.9 ng L^-1. The spiked average recoveries of PAHs in natural water samples ranged from 92.5% to 105.2%. The promising results indicated that MNPs@PAMAM-G2.0@GO could be employed to efficiently extract PAHs from aqueous samples.

Biomass poplar catkin fiber-based superhydrophobic aerogel with tubular-lamellar interweaved neurons-like structure

Superhydrophobic aerogels are attractive candidates in controlling oil spills. The major challenges for existing aerogels are the construction of mechanical endurance as well as accessible of building materials. Herein, a newfangled biomass superhydrophobic aerogel (M-PCF/CS) with both superior compressibility and oil caption speed is fabricated by assembling poplar catkin fiber (PCF) hollowed-out shell of 330 nm and chitosan (CS) into tubular-lamellar interweaved neurons-like structure. The resultant aerogels (porosity ~ 96.12%), with flexuous PCF as the elastic buffer and second-pore capillaries, exhibit large longitudinal and transverse compressibility, endurable fatigue tolerance, fast oil sorption rate with a capacity of 28.8-78.1 g/g at 5-25 s. In parallel, the aerogels are tolerant of NaCl, UV radiation, and organic solvents without superhydrophobic variation and a case of oil spill remediation via pump-supported experiment shows that the aerogels facilely achieve continuous oil recycling from seawater by 23052-43956 L·m^-2·h^-1. Furthermore, the resultant M-PCF/CS, with assistance of an oscillator, can be applied to separate oil/water emulsions with efficiency of 98.07-99.11%. The successful fabrication of this material provides a new design strategy for the construction of mechanically robust aerogels for speedy and economical cleanup of oil pollutants from water.

Chitosan magnetic graphene grafted polyaniline doped with cobalt oxide for removal of Arsenic(V) from water

The present study reports the successful functionalization/magnetization of bio-polymer to produce chitosan-magnetic graphene oxide grafted polyaniline doped with cobalt oxide (ChMGOP-Co₃O₄). Analytical techniques furrier transform infra-red (FT-IR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) were used to confirm the formation of ChMGOP-Co₃O₄. The effects of several experimental factors (solution pH, adsorbent dosage and coexisting ions) on the uptake of As(V) ions using ChMGOP-Co₃O₄ were examined through batch experiments. As(V) removal process was validated by experimentally and theoretically investigating the adsorption capacity, rate, and thermal effects. Thermodynamic parameters such as free energy (ΔG°), entropy (ΔS°) and enthalpy (ΔH°) were also calculated and were used to explain the mechanism of adsorption. Based on the results, the sorbent showed a high adsorption capacities (90.91 mg/g) at favorable neutral pH and superior removal efficiencies as high as 89% within 50 min. In addition, the adsorption isotherm followed the Langmuir isotherm in compare to the Freundlich, due to its higher R² value (0.992 < 0.941). Meanwhile, the kinetic data revealed that the of As(V) adsorption was controlled by pseudo-second-order. Overall, the adsorption mechanism studies revealed a spontaneous endothermic nature with predominance of physisorption over chemisorption. This study indicated that ChMGOP-Co₃O₄ is an exceptional novel adsorbent material for the efficient isolation of As(V) from aqueous media.

Ionic liquid-based magnetic nanoparticles for magnetic dispersive solid-phase extraction: A review

Due to their highly tunable nature and outstanding physicochemical properties, ionic liquids (ILs) have been widely reported for use in the synthesis of multitudinous magnetic nanoparticles (MNPs). IL-based magnetic nanoparticles (IL-MNPs) have great potential in magnetic dispersive solid-phase extraction (MDSPE). At present, IL-MNPs have been successfully applied in the pretreatment of MDSPE samples from medicines, pesticides, veterinary drugs, heavy metals, dyes, additives, and proteins in agricultural products, foods and beverages, environmental water, and biological samples. In this review, the preparation of IL-MNPs and their application in MDSPE are comprehensively summarized. The structural characteristics of the introduced ILs used to prepare the IL-MNPs and the synthetic routes employed to obtain the IL-MNPs are described, including physical coating and chemical bonding methods. The IL-MNPs are then classified and described according to different modified materials, including silica-based materials, carbon-based materials, metal-organic frameworks, molecularly imprinted polymers and other interesting large/small molecules. Finally, the research prospects and development directions of IL-MNPs in the context of MDSPE are further identified.

Development of a rapid efficient solid-phase microextraction: An overhead rotating flat surface sorbent based 3-D graphene oxide/ lanthanum nanoparticles @ Ni foam for separation and determination of sulfonamides in animal-based food products

In this study, an overhead rotating flat surface sorbent based solid-phase microextraction was developed as a rapid and efficient method for simultaneous separation and determination of sulfonamides in animal based-food products. 3D graphene oxide/ lanthanum nanoparticles @ Ni foam was introduced as a novel selective sorbent. SEM-EDX and FT-IR techniques were applied for characterization of the sorbent. At optimum conditions, the linear ranges of 0.4-700.0 (µg L^-1), 0.3-900.0 (µg L^-1), and 0.25-500 (µg L^-1) and the enrichment factors of 606.8, 604.3, 608.9 were obtained for SDZ, SMX, and SMZ, respectively. The LOD (S/N = 3) of 0.14, 0.11, 0.08 (µg L^-1) were achieved for SDZ, SMX, and SMZ, respectively. The intra-day and inter-day precision (%) (five days, n = 7) for the concentration of 100 µg L^-1 were less than 4.3 and 3.8, respectively. The recoveries over 90.0 % revealed high capability of the method for utilization in complex matrixes.

Polyaniline spinel particles with ultrahigh-performance liquid chromatography tandem mass spectrometry for rapid vitamin B9 determination in rice

Rice is an important crop that provides energy and nutrients to humans, which undergoes the aging process, the quality decline is related to the exogenous storage conditions and the change of own enzyme activity. However, due to the complex composition of rice and serious matrix interference, the ageing identification of rice is still challenging. Hence, a novel spinel particles ZnFe₂O₄@PANI was designed and synthesized for adsorption and determination of vitamin B₉, which can be used to distinguish rice in different years and analyze the degree of aging. The ZnFe₂O₄@PANI showed large specific surface area and fast mass transfer rate with good linear correlation coefficient (R² = 0.9965), satisfactory recoveries (85.1%-99.9%) and relative standard deviations (RSD, 9.3%). Moreover, the π-π electron-donor-acceptor (EDA) and intermolecular hydrogen-bonding interactions of polyaniline coating provided selective adsorption on vitamin B₉. Adsorption thermodynamics study suggested that the adsorption reactions were spontaneous, endothermic and thermodynamically favorable. Finally, ZnFe₂O₄@PANI was used to evaluate vitamin B₉ in rice from different years, which laid a theoretical foundation for exploring the relationship between vitamin changes and the aging degree of the rice.

Miniaturized green sample preparation approaches for pharmaceutical analysis

The development of green sample preparation procedures is an extremely important research field in which more and more applications are constantly being proposed in different areas, including pharmaceutical analysis. This review article is aimed at providing a general overview of the development of miniaturized green analytical sample preparation procedures in the pharmaceutical analysis field, with special focus on the works published between January 2017 and July 2021. Particular attention has been paid to the application of environmentally friendly solvents and sorbents as well as nanomaterials or high extraction capacity sorbents in which the solvent volumes and reagents amounts are drastically reduced, with their subsequent advantages from the sustainability point of view.

Phenylboronic acid-functionalized cross-linked chitosan magnetic adsorbents for the magnetic solid-phase extraction of benzoylurea pesticides

In this study, a 4-formylphenylboronic acid-modified cross-linked chitosan magnetic nanoparticle (FPBA@CCHS@Fe₃ O₄ ) was fabricated. The synthesized material was utilized as the magnetic solid-phase extraction adsorbent for the enrichment of six benzoylurea pesticides. In addition to B-N coordination, FPBA@CCHS@Fe₃ O₄ interacts with benzoylureas through hydrogen bonds and π-π stacking interaction on account of rich active groups (amino and hydroxyl) and aromatic rings in structure. Compared to traditional extraction methods, less adsorbent (20 mg) and reduced extraction time (3 min) were achieved. The adsorbent also exhibited good reusability (no less than 10 times). Coupled with a high-performance liquid chromatography-diode array detector, satisfactory recoveries (89.1-103.9%) and an acceptable limit of detection (0.2-0.7 μg/L) were obtained. Under optimized conditions, the established method was successfully applied to the tea infusion samples from six major tea categories with acceptable recoveries ranging from 76.8 to 110%, indicating its application potential for the quantitative detection of pesticides in complex matrices.

Efficiency of calcined Aluminum-Magnesium layered double hydroxide for adsorption of aflatoxin M1 from solution and matrix of milk

Detoxification of aflatoxin M₁ from solution and milk using layered double hydroxides was investigated. The Aluminum-Magnesium layered double hydroxide (Al-Mg LDH) and Iron-Magnesium layered double hydroxide (Fe-Mg LDH) were selected in their calcined and non-calcined forms to evaluate the effect of the calcination on detoxification. These materials were produced using the co-precipitation method. Preliminary adsorption tests confirmed use of Al-Mg LDH as the selected adsorbent. Characteristics of the adopted adsorbent were studied and confirmed by XRD, FTIR, SEM, and BET methods. Effects of the initial content of aflatoxin, amount of the adsorbents and detoxification time were investigated. Influence of the adsorbents on the nutritional aspects of milk were also studied. The study showed that while the non-calcined forms of LDH were not able to adsorb aflatoxin M₁ more than 23%, the calcined form of Al-Mg LDH exhibited 100% adsorption in the solutions and about 70-100% in the contaminated milk samples. The reason is pointed to the fact that calcination of Al-Mg LDH considerably increased the surface area, the total pore volume, and the pore size of the material. Multivariate regression analysis and calculation of the Pearson correlation factor showed that the remained aflatoxin at each time was more strongly correlated with the initial amount of aflatoxin and the elapsed time and less strongly with the amount of the adsorbent. It was found that the adsorption isotherms fitted to the Freundlich equation with a high adsorption capacity of 555.5 mg g-1. PRACTICAL APPLICATION: This study is focused on examining ability of layered double hydroxides (LDH) for adsorbing AFM₁ . LDHs are promising layered materials due to some of their interesting characteristics, such as ease of synthesis and uniqueness of structure. In practice, results of this study can be used for detoxification of aflatoxin, especially in milk, at high efficiency in shorter time durations.

Magnetic nanoadsorbents for micropollutant removal in real water treatment: a review

Pure water will become a golden resource in the context of the rising pollution, climate change and the recycling economy, calling for advanced purification methods such as the use of nanostructured adsorbents. However, coming up with an ideal nanoadsorbent for micropollutant removal is a real challenge because nanoadsorbents, which demonstrate very good performances at laboratory scale, do not necessarily have suitable properties in in full-scale water purification and wastewater treatment systems. Here, magnetic nanoadsorbents appear promising because they can be easily separated from the slurry phase into a denser sludge phase by applying a magnetic field. Yet, there are only few examples of large-scale use of magnetic adsorbents for water purification and wastewater treatment. Here, we review magnetic nanoadsorbents for the removal of micropollutants, and we explain the integration of magnetic separation in the existing treatment plants. We found that the use of magnetic nanoadsorbents is an effective option in water treatment, but lacks maturity in full-scale water treatment facilities. The concentrations of magnetic nanoadsorbents in final effluents can be controlled by using magnetic separation, thus minimizing the ecotoxicicological impact. Academia and the water industry should better collaborate to integrate magnetic separation in full-scale water purification and wastewater treatment plants.

Current Applications of Magnetic Nanomaterials for Extraction of Mycotoxins, Pesticides, and Pharmaceuticals in Food Commodities

Environmental pollutants, such as mycotoxins, pesticides, and pharmaceuticals, are a group of contaminates that occur naturally, while others are produced from anthropogenic sources. With increased research on the adverse ecological and human health effects of these pollutants, there is an increasing need to regularly monitor their levels in food and the environment in order to ensure food safety and public health. The application of magnetic nanomaterials in the analyses of these pollutants could be promising and offers numerous advantages relative to conventional techniques. Due to their ability for the selective adsorption, and ease of separation as a result of magnetic susceptibility, surface modification, stability, cost-effectiveness, availability, and biodegradability, these unique magnetic nanomaterials exhibit great achievement in the improvement of the extraction of different analytes in food. On the other hand, conventional methods involve longer extraction procedures and utilize large quantities of environmentally unfriendly organic solvents. This review centers its attention on current applications of magnetic nanomaterials and their modifications in the extraction of pollutants in food commodities.