Application of magnetic nanoparticles for magnetic solid-phase extraction in preparing biological, environmental and food samples

Zeolitic imidazolate framework-8 coated Fe3O4@SiO2 composites for magnetic solid-phase extraction of bisphenols

A new magnetic composite material ZIF-8 coated Fe₃O₄@SiO₂ was employed for preconcentration and detection of trace BPs in water and plastic products.

Magnetic molecularly imprinted conducting polymer for determination of praziquantel enantiomers in milk

A new selective adsorbent based on magnetic molecularly imprinted conducting polymer was firstly synthetized and applied to the magnetic solid phase extraction (MSPE) for the determination of PZQ enantiomers in milk samples.

Extraction of phenylurea herbicides from rice and environmental water utilizing MIL-100(Fe)-functionalized magnetic adsorbents

In this paper, a novel method is reported for the extraction and enrichment of phenylurea herbicides (PUHs) from rice and environmental water samples using MIL-100(Fe)-functionalized magnetic nanoparticles as adsorbents.

Thermoregulated extraction of luteolin under neutral conditions using oligo(ethylene glycol)-based magnetic nanoparticles with Wulff-type boronate affinity

Oligo(ethylene glycol)-based thermoresponsive polymers with Wulff-type boronate affinity were anchored on magnetic nanoparticles. The resultant magnetic nanoparticles were used as sorbents for extracting luteolin, a cis-diol-containing model analyte. By exploiting the thermoresponsive properties and Wulff-type boronate affinity of the sorbents, target adsorption at room temperature (25 °C) and target release at high temperature (40 °C) were achieved under neutral conditions without pH alteration. The proposed thermoregulated extraction method was favorable for automated boronate affinity extraction, preventing degradation of the target and avoiding acidic elution for breaking Wulff-type boronate sites. Compared to reported sorbents for extracting luteolin, the sorbents possessed higher maximum adsorption capacity (98.7 mg g^-1) with acceptable sensitivity, simplified operation procedure, and mild extraction condition. Furthermore, the sorbents were applied in thermoregulated extraction of luteolin from honey samples. Satisfactory recoveries in the range of 83.2% - 89.1% with RSD ranging from 2.2% to 4.6% were achieved. The results demonstrated that this work provided a new research direction to design and synthesize efficient thermoresponsive materials for recognition and release of cis-diol compounds under neutral conditions.

Magnetic Particles-Based Analytical Platforms for Food Safety Monitoring

Magnetic nanoparticles (MNPs) have attracted growing interest as versatile materials for the development of analytical detection and separation platforms for food safety monitoring. This review discusses recent advances in the synthesis, functionalization and applications of MNPs in bioanalysis. A special emphasis is given to the use of MNPs as an immobilization support for biomolecules and as a target capture and pre-concentration to increase selectivity and sensitivity of analytical platforms for the monitoring of food contaminants. General principles and examples of MNP-based platforms for separation, amplification and detection of analytes of interest in food, including organic and inorganic constituents are discussed.

Advances in the Application of Magnetic Nanoparticles for Sensing

Magnetic nanoparticles (MNPs) are of high significance in sensing as they provide viable solutions to the enduring challenges related to lower detection limits and nonspecific effects. The rapid expansion in the applications of MNPs creates a need to overview the current state of the field of MNPs for sensing applications. In this review, the trends and concepts in the literature are critically appraised in terms of the opportunities and limitations of MNPs used for the most advanced sensing applications. The latest progress in MNP sensor technologies is overviewed with a focus on MNP structures and properties, as well as the strategies of incorporating these MNPs into devices. By looking at recent synthetic advancements, and the key challenges that face nanoparticle-based sensors, this review aims to outline how to design, synthesize, and use MNPs to make the most effective and sensitive sensors.

Assessment of magnetic core-shell mesoporous molecularly imprinted polymers for selective recognition of triazoles residual levels in cucumber

Functional magnetic nanomaterials based on molecular imprinting technique were successfully prepared on the surface of modified Fe₃O₄. Transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffractometer, and vibrating sample magnetometry were applied for characterization of the synthesized magnetic nanoparticles. The magnetic molecularly imprinted polymers (MMIPs) exhibited satisfactory magnetic response, specific recognition, and excellent adsorption capacity toward triazoles (maximum adsorption capacity of 9202.9 μg g^-1 for triadimefon). The obtained MMIPs were further used as magnetic dispersive solid-phase extraction (MDSPE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for detection of 20 triazoles in cucumber spiked at different levels. The mean recoveries were ranged from 79.9% to 110.3% and relative standard deviations (RSDs) were <11.2% (n = 5). Herein, we report a simple, rapid, environmentally friendly, and magnetic stuff recyclable approach for triazoles residual analysis in complicated agricultural products.

Applications of Green Chemistry Approaches in Environmental Analysis

Background:

Green chemistry is the application of methodologies and techniques to reduce the use of hazardous substances, minimize waste generation and apply benign and cheap applications.

Methods:

In this article, the following issues were considered: greener solvents and reagents, miniaturization of analytical instrumentation, reagent-free methodologies, greening with automation, greener sample preparation methods, and greener detection systems. Moreover, the tables along with the investigated topics including environmental analysis were included. The future aspects and the challenges in green analytical chemistry were also discussed.

Results:

The prevention of waste generation, atomic economy, use of less hazardous materials for chemical synthesis and design, use of safer solvents, auxiliaries and renewable raw materials, reduction of unnecessary derivatization, design degradation products, prevention of accidents and development of real-time analytical methods are important for the development of greener methodologies.

Conclusion:

Efforts should also be given for the evaluation of novel solid phases, new solvents, and sustainable reagents to reduce the risks associated with the environment. Moreover, greener methodologies enable energy efficient, safe and faster that reduce the use of reagents, solvents and preservatives which are hazardous to both environment and human health.

Innovative Configurations of Sample Preparation Techniques Applied in Bioanalytical Chemistry: A Review

Background:

Recently, in all fields of analytical chemistry, increased attention has been paid to extraction procedures and instrumental methods, which are easily scalable and are able to automate in order to improve the “high-throughput” capability.

Introduction:

The main goal of these applications relates to an improvement of the precision in the quantitative analysis, reduction of different sources of errors, decrease the analysis time and, in general, improve the analytical performances. Often these points can be in contrast to each other, not allowing to achieve the expected result but forcing a compromise between the objectives of the method and the analytical performance.

Methods:

In this review, following the evolution of the (micro)extraction procedures and instrument configurations, the recent procedures used in bioanalytical chemistry are critically evaluated. The aim of this paper is providing an overview of the approaches available in order to perform on-line coupling of various extraction techniques with chromatographic methods for the analysis of different compounds in various samples. Furthermore, a comparison between off-line and on-line systems, advantages of on-line systems applied on major extractive techniques and future perspectives are described.

Result:

The extraction methods suitable for on-line coupling covered in this review are: liquid-liquid extraction (LLE), solid phase extraction (SPE), solid phase microextraction (SPME), dispersive liquid- liquid microextraction (DLLME), microextraction by packed sorbent (MEPS), supercritical fluid extraction (SFE) and fabric phase sorptive extraction (FPSE).

Conclusion:

An overview of the micro-extraction techniques mentioned above was provided, making a comparison between them and focusing attention on future perspectives.

Dispersive Magnetic Solid-Phase Extraction Coupled to Direct Analysis in Real Time Mass Spectrometry for High-Throughput Analysis of Trace Environmental Contaminants

Coupling dispersive magnetic solid-phase extraction (DMSPE) to direct analysis in real time mass spectrometry (DART-MS) with a newly developed metal iron probe enables high-throughput, sensitive detection of herbicides such as triazine in environmental waters. Magnetic graphene oxide was used as a dispersive sorbent because it increased adsorption capacity in the DMSPE process. The planar structure and excellent thermal conductivity of graphene oxide facilitated the desorption and ionization of target analytes in DART-MS analysis. The iron probe, which is designed to fit into the moving trail of the DART interface, served as the sorbent collector as well as the support for the magnetic graphene oxide after DMSPE, and was put directly into the DART system. The ratio of magnetic core to graphene oxide in the nanoparticles and other key parameters in DMSPE and DART-MS procedures were systematically investigated and optimized. In addition, the presence of water on the sorbent proves to have a significant effect on DART-MS analysis. No organic solvents are used in this method, and the reusable iron probe is of low cost. Under the optimal conditions, limits of detection were found in the range of 1.6-152.1 ng/L for the triazines. Recovery and reproducibility were found to be in the ranges of 87.5-115.0% and 1.9-10.2%, respectively, for the six herbicides studied. The analytical performance of the DMSPE-DART-MS method indicated that applications for trace analysis of other compounds in liquid samples are also possible.

Metal-Organic Frameworks for Food Safety

Food safety is a prevalent concern around the world. As such, detection, removal, and control of risks and hazardous substances present from harvest to consumption will always be necessary. Metal-organic frameworks (MOFs), a class of functional materials, possess unique physical and chemical properties, demonstrating promise in food safety applications. In this review, the synthesis and porosity of MOFs are first introduced by some representative examples that pertain to the field of food safety. Following that, the application of MOFs and MOF-based materials in food safety monitoring, food processing, covering preservation, sanitation, and packaging is overviewed. Future perspectives, as well as potential opportunities and challenges faced by MOFs in this field will also be discussed. This review aims to promote the development and progress of MOF chemistry and application research in the field of food safety, potentially leading to novel solutions.

A review of developments and applications of thin-film microextraction coupled to surface-enhanced Raman scattering

Surface-enhanced Raman scattering (SERS) greatly expands the applications of Raman spectroscopy and is a promising technique for food safety, environmental analysis, and public safety. Thin-film microextraction (TFME) provides an efficient sample preparation method for SERS to improve its selectivity and detection efficiency. This review comprehensively describes the development and applications of SERS and TFME, including the history, mechanisim, and active substrate of SERS and the theory, device, forms, and practical applications of TFME. The applications of TFME-SERS in food safety and environment monitoring are discussed, which could improve their advantages. TFME extracts and enriches the target analytes to eliminate the interfering substance, providing a facial way for SERS to analyze the target analytes in complex matrices. The development of TFME-SERS technology not only expands the application range of TFME, but greatly improves the anti-interference ability and detection sensitivity of SERS. Thus, the established methods are fast, convenient, and highly sensitive. This technology is potential to be applied in the on-site and real-time detection.

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

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

Facile Preparation of Dual-Shell Novel Covalent-Organic Framework Functionalized Magnetic Nanospheres Used for the Simultaneous Determination of Fourteen Trace Heterocyclic Aromatic Amines in Nonsmokers and Smokers of Cigarettes with Different Tar Yields Based on UPLC-MS/MS

The facile preparation, characterization, and application of novel dual-shell TpBD (a kind of covalent-organic framework) coated magnetic nanospheres as sorbents for simple, fast, and high selectivity capture of 14 heterocyclic aromatic amines (HAAs) are reported. Quantum chemistry theory calculations were conducted to directly and quantifiably describe the multiple interactions, including π-π, hydrogen bonding, cation-π, static electricity, and ion-exchange, between TpBD and heterocyclic aromatic amines. The excellent adsorption capacity of TpBD coated magnetic nanospheres was further evaluated by extraction of 14 HAAs from nonsmokers' and smokers' urine samples. Under the optimized conditions, the magnetic solid phase extraction process can be completed with high recovery ranging from 95.4% to 129.3%. After being washed with acetonitrile and water successively, the collected sorbents can be easily recycled and reused five times without any significant difference in performance. Coupled with the ultra performance liquid chromatography-tandem mass spectrometer detection, the exposure level of HAAs in nonsmokers and smokers smoking cigarettes with different tar yields were successfully explored. And, this implied that the robust method based on the versatile TpBD coated dual-shell magnetic nanospheres sorbents represents a great potential application in the analysis of disease markers and body fluids.

Determination of trace amounts of aromatic amines after magnetic solid-phase extraction using silver-modified Fe3 O4 /graphene nanocomposite

In this work, a fast and simple magnetic dispersive solid phase extraction methodology was developed utilizing Ag@magnetite nanoparticles@graphene nanocomposite as an efficient magnetic nanosorbent for preconcentration and determine of five aromatic amines in water samples. The sorbent was characterized by diverse characterization techniques. After the extraction, high-performance liquid chromatography with UV detection was utilized to analysis the aromatic amines. The effects of different factors on the extraction process were studied thoroughly via design of experiment and desirability function. Detection limits and linear dynamic ranges were obtained in the range of 0.10-0.20 and 0.3-300 μg/L, respectively. The relative standard deviations (n = 5) were in the range of 4.3-6.5%. Eventually, the method was employed for determination of target aromatic amines in various water samples.

Functionalization of amino terminated carbon nanotubes with isocyanates for magnetic solid phase extraction of sulfonamides from milk and their subsequent determination by liquid chromatography-high resolution mass spectrometry

A simple modification method was developed for the functionalization of amino terminated carbon nanotubes (CNT-NH₂) by using isocyanates as modifiers via the nucleophilic addition reaction. Two types of functionalized magnetic carbon nanotubes (MCNT) were prepared through deposition of magnetic nanoparticles on CNT-NH₂ and modification with different isocyanates. p-Tolyl-functionalized MCNT (Tol-MCNT) with better adsorption performance were selected as adsorbent for magnetic solid phase extraction (MSPE), which could extract sulfonamides (SAs) from various milk samples with a enrichment factor of about 30 after optimization. By combining the MSPE with liquid chromatography-high resolution mass spectrometry (LC-HRMS), a new method was developed. Both skimmed and whole milk samples of three brands were analyzed with this method, and 4 SAs including sulfadiazine, sulfisomidine, sulfamethazine and sulfameter were detected with the concentration from unquantifiable to 72 ng/L, which were all well below the maximum residue limits in milk according to the regulations of China and EU.

Dispersive Solid Phase Extraction Using Magnetic Nanoparticles Performed in a Narrow-Bored Tube for Extraction of Atorvastatin, Losartan, and Valsartan in Plasma

Purpose: In this investigation, a new version of magnetic solid phase extraction (MSPE) performed in a narrow–bore tube has been proposed. In this study, hydrophobic octyl (C₈) functionalized Fe₃O₄ magnetic nanoparticles (MNPs) stabilized by SiOH groups (Fe₃O₄@SiO₂@C₈) are used as magnetic nano–sorbents for the extraction of cardiovascular drugs from human plasma prior to their determination by high performance liquid chromatography–photodiode array detection.

Methods: After precipitation of the plasma proteins, the supernatant is diluted with deionized water and filled into the narrow–bore tube. Then mg–level of the sorbent is added into the tube. The sorbent is dispersed and moved down through the solution instead of passing the solution from the cartridge. Using an external magnet, the collected nano–sorbents at the bottom of the tube are transferred on top of the solution and released to move down through the solution for three times to increase the extraction efficiency.

Results: The linearity of the assay was ranging from 0.4–500 mg mL^-1. The limits of detection and quantification of the method were obtained in the ranges of 0.05–0.07 and 0.16–0.24 mg L^-1, respectively. The extraction recoveries were obtained in the range of 31–49%. Intra– and inter–day precisions were calculated and obtained in the ranges of 5–8 and 7%–9% for 0.5 mg L^-1 of each analyte, and 5–6 and 6%–8% for 2 mg L^-1 of each analyte, respectively.

Conclusion: The proposed method was successfully used in determination of the studied drugs in patient’s plasmas.

Current direction and advances in analytical sample extraction techniques for drugs with special emphasis on bioanalysis

Analytical techniques may not be compatible or sufficiently sensitive to the analytes, unless it undergoes a specific sample extraction procedure. Sample extraction can be considered as one of the key steps in analysis. Analysis of a poorly treated sample may produce inferior quality of analytical data. Continuous advancement and development of newer sample extraction techniques such as solid phase microextraction, ultrasound, magnetically and microwave assisted magnetic extraction; electro-membrane extraction and dried blood spotting are to address the shortcomings of the existing techniques and to provide more automation, minimizing preparation time and make them high throughput. This review summarizes the suitability of application of the advanced sample preparation techniques available for chemical and bioanalysis in a comprehensive manner. This review also provides a scientific guidance for selecting the appropriate sample extraction technique based on sample type.

Selective magnetic mercury(ii) ion capturing ligand-doped silica gel for water analysis

This study demonstrates a simplified method for the synthesis of a magnetic adsorbent, which is selective towards the adsorption of mercury(ii) ions (Hg²⁺).