Solid Phase Microextraction: Apparatus, Sorbent Materials, and Application

A three-dimensional hierarchical porous graphene aerogel as a fiber coating for headspace solid-phase microextraction: Enhancing the enrichment and detection of polychlorinated naphthalenes in fish

In this study, a novel three-dimensional hierarchical porous deep eutectic solvents-modified graphene aerogel (3D DES-GA) was synthesized for use as a solid-phase microextraction (SPME) fiber coating. The SPME fiber was characterized by its fluffy and hierarchical porous structure, uniform thickness, and rapid mass transfer capabilities. This fiber demonstrated a lifetime (≥160 uses) and excellent precision (with relative standard deviations of 2.4-6.6% for single fiber and 6.0-9.8% for fiber-to-fiber repeatability). The SPME fiber also exhibited remarkable extraction performance for polycyclic aromatic hydrocarbons and polychlorinated biphenyls, which are common persistent organic pollutants in environmental samples. When combined with gas chromatography-tandem mass spectrometry, the method allowed for high-efficiency extraction (enrichment factors ranging from 1225 to 4652 folds) and sensitive determination (limit of detection ranging from 0.010 to 0.056 pg g-1) of polychlorinated naphthalenes (PCNs) in complex samples. To validate this method, we applied it to the determination of four PCNs in five types of fish tissues. The results revealed the presence of 1-chloronaphthalene at concentrations of 7.0 ± 2.9-34.8 ± 2.1 pg g-1 and 1,4-dichloronaphthalene at concentrations of 6.0 ± 0.3-10.9 ± 1.4 pg g-1 in three fish species. Compared with reported sample pretreatment methods reported in the literature, this proposed headspace SPME method offers additional advantages, including simplicity of operation and reduced sample and organic solvent consumption.

Bifunctional magnetic nanoparticles with ion imprinting for improving the flow through determination of ultratraces of Cd(II) using magnetic preconcentration

A novel bifunctional magnetic sorbent with mercapto and amino groups and ion imprinting (MBII) was synthesized using a one-step aqueous sol-gel process for preconcentration and determination of Cd(II) ions. MBII was employed as a microcolumn (MC) filler in a flow-through system coupled to GFAAS. The magnetic properties of the solid allowed microcolumn magnetic solid-phase extraction (MCMSPE) to be performed by simply including a single circular magnet around the MC. This assembly enabled complete attachment of the solid to the MC wall leaving a central void to facilitate higher sample flow rates without blockage or material loss. For comparison, a bifunctional magnetic solid without imprinting (MBNI) was also synthesized and evaluated. Both MBII and MBNI were characterized by FTIR, SEM, EDX, BET and magnetization measurements. The results showed the preservation of the magnetic core, its superparamagnetism and the functional groups in the solid. Batch studies revealed a maximum adsorption capacity for both materials at pH around 6 with equilibrium reached within 5 minutes. The advantages were reflected in the maximum adsorption capacity of MBII, which was found to be 2.5 times greater than that of MBNI. Both adsorbents were compared as MC fillers for dynamic preconcentration in MCMSPE systems. Under optimized conditions, MBNI showed a PCF of 125 and MBII of 250. The higher selectivity of MBII was corroborated by interfering ion studies. The analytical performance parameters for the proposed method using MBII as an adsorbent showed a detection limit of 0.05 ng L-1, a linear range of 2.0-80 ng L-1, an RSD% of 2.2 (n = 7; 20 ng L-1) and a lifetime of more than 300 preconcentration-elution cycles without loss of sensitivity or need for refilling. The method was successfully applied to the determination of trace Cd(II) in osmosis, lake and tap water with recoveries ranging from 98 to 105%. Comparison of these results with those of similar reported methods showed a considerable improvement primarily attributed to the combined effect of MBII's higher retention capacity and its magnetic properties that allowed higher sample flow rates and, thus, enhanced figures of merit.

Solid-phase microextraction - a future technique in pharmacology and coating trends

Traditional sample preparation techniques based on liquid-liquid extraction (LLE) or solid-phase extraction (SPE) often suffer from a major error due to the matrix effects caused by significant co-extraction of matrix components. The implementation of a modern extraction technique such as solid-phase microextraction (SPME) was aimed at reducing analysis time and the use of organic solvents, as well as eliminating pre-analytical and analytical errors. Solid-phase microextraction (SPME) is an innovative technique for extracting low molecular weight compounds (less than 1500 Da) from highly complex matrices, including biological matrices. It has a wide range of applications in various types of analysis including pharmaceutical, clinical, metabolomics and proteomics. SPME has a number of advantages over other extraction techniques. Among the most important are low environmental impact, the ability to sample and preconcentrate analytes in one step, simple automation, and the ability to extract multiple analytes simultaneously. It is expected to become, in the future, another method for cell cycle research. Numerous available literature sources prove that solid-phase microextraction can be a future technique in many scientific fields, including pharmaceutical sciences. This paper provides a literature review of trends in SPME coatings and pharmacological applications.

Solid phase microextraction device coupled with miniature mass spectrometry and mathematical model of its ion chronogram

Modern solid phase microextraction (SPME) device linked with mass spectrometry (SPME-MS) has evolved from producing ion chronogram as flat noisy signal to as unimodal-like signal. We designed a SPME device, which is closer in morphology to LC column, linked it with a miniature mass spectrometer (SPME-Mini MS), and proposed a mathematical model that elution of compound from the SPME device is equivalent to overlay of elution of the compound from the infinite LC columns with the lengths between 0 and the length of the device and it can generate an ion chronogram as right-skew unimodal signal. Rhodamine B as analyte was used for experimental verification and its unimodal signal was used to fit the parameters of a computer simulation program based on the model. The experimental results and simulations empirically cross-confirmed that SPME-Mini MS can generate ion chronogram as clean right-skew unimodal signal. Furthermore, the SPME-Mini MS system was used for quantitative analysis of psychotropic drugs (i.e. risperidone and aripiprazole) in artificial urine. The results preliminarily demonstrated that the system can utilize area under unimodal signal for quantitative analysis and has potential to be applied for on-site, fast and accurate quantification of drugs and other compounds.

Controlled construction of 2D hierarchical core-shell ZnO/MnO2 nanosheets on Nitinol fiber with enhanced adsorption performance for selective solid-phase microextraction of trace polycyclic aromatic hydrocarbons in water samples

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs) are an important class of potentially toxic persistent organic pollutants in environmental water. Their concentrations are usually too low to allow for direct determination with analytical instruments, and the preconcentration is required prior to instrumental analysis. Solid phase microextraction (SPME) is considered as a high-performance green sample preparation technique for volatile and non-volatile organic compounds due to its high enrichment factor. In fact, the nature of SPME coatings governs the adsorption performance. Therefore, more efforts have devoted to the controlled construction of novel long-life SPME fibers with enhanced adsorption performance and improved adsorption selectivity.

RESULTS

2D hierarchical core-shell ZnO/MnO2 nanosheets (NSs) were constructed on a Nitinol (NiTi) fiber substrate by layer-by-layer assembly for enhanced and selective SPME of PAHs. Firstly, hexagonal ZnO NSs were electrodeposited on the NiTi substrate. Subsequently smaller secondary MnO2 NSs were uniformly grown on the surface of ZnO NSs by a facile hydrothermal oxidation process. ZnO NSs were well protected by the chemically stable MnO2 shell, making the coating highly durable and efficient for SPME application. Meanwhile, the ZnO/MnO2 NSs coating demonstrated superior adsorption performance for PAHs. After the optimization of SPME conditions, the proposed SPME-HPLC-UV method exhibited good analytical performance for preconcentrating and determining trace PAHs with wide linear ranges (0.03-200 μg L-1) and low LODs (0.005-0.112 μg L-1) as well as good repeatability (1.4%-6.9%) and fiber-to-fiber reproducibility (5.3%-7.1%). Moreover, the proposed method showed good precision and recovery in the preconcentration and determination of target PAHs in real water samples.

SIGNIFICANCE

As compared with representative commercially available fibers, the NiTi@ZnO/MnO2 NSs fiber showed enhanced adsorption efficiency and improved adsorption selectivity for PAHs. The constructed fiber can be used as an alternative to commercial fibers for the adsorption and preconcentration of target PAHs in the environmental water samples. Moreover, the preparation strategy is expected to provide new insights into the precisely controlled construction of the efficient and stable core-shell bimetallic oxide nanostructures on the superielastic NiTi-based fibers.

Chromatographic Methods for the Determination of Organic Pollution in Urban Water: A Current Mini Review

The number of pollutants and chemicals with the potential to reach the environment is still largely unknown, which poses great challenges for researchers in various fields of science, environmental scientists, and analytical chemists. Chromatographic techniques, both gas chromatography (GC) and liquid chromatography (LC) coupled with different types of detection, are now invaluable tools for the identification of a wide range of chemical compounds and contaminants in water. This review is devoted to chromatographic techniques GC-MS, GC-Orbitrap-MS, GC-MS/MS, GC-HRMS, GC × GC-TOFMS, GC-ECD, LC-MS/MS, HPLC-UV, HPLC-PDA, UPLC-QTOFMS, used to determinate emerging organic contaminants in aquatic media, mainly in urban water, published in the scientific literature over the past several years. The article also focuses on sample preparation methods used in the analysis of aqueous samples. Most research focuses on minimizing the number of sample preparation steps, reducing the amount of solvents used, the speed of analysis, and the ability to apply it to a wide range of analytes in a sample. This is extremely important in the application of sensitive and selective methods to monitor the status of urban water quality and assess its impact on human health.

Current analytical strategies for the determination of resveratrol in foods

Resveratrol, a non-flavonoid polyphenolic compound, possesses various beneficial properties such as anti-cancer, anti-aging, anti-bacterial, and antioxidant effects. It is naturally produced by many plants in response to stimulation. However, the content of resveratrol in natural plants can vary significantly, ranging from micrograms to milligrams per kilogram. As the demand for resveratrol increases, the development of methods for extracting and quantifying resveratrol in food has become a rapidly growing field in recent years. This review aims to comprehensively summarize the progress made in resveratrol analysis in food over the past decade (2012-2022), with a specific focus on the latest advancements in extraction and detection technologies. The objective is to offer a valuable reference for further research and utilization of resveratrol in various food applications.

Recent Progress on Green New Phase Extraction and Preparation of Polyphenols in Edible Oil

With the proposal of replacing toxic solvents with non-toxic solvents in the concept of green chemistry, the development and utilization of new green extraction techniques have become a research hotspot. Phenolic compounds in edible oils have good antioxidant activity, but due to their low content and complex matrix, it is difficult to achieve a high extraction rate in a green and efficient way. This paper reviews the current research status of novel extraction materials in solid-phase extraction, including carbon nanotubes, graphene and metal-organic frameworks, as well as the application of green chemical materials in liquid-phase extraction, including deep eutectic solvents, ionic liquids, supercritical fluids and supramolecular solvents. The aim is to provide a more specific reference for realizing the green and efficient extraction of polyphenolic compounds from edible oils, as well as another possibility for the future research trend of green extraction technology.

Automated and semi-automated packed sorbent solid phase (micro) extraction methods for extraction of organic and inorganic pollutants

In this study, the packed sorbent solid phase (micro) extraction methods from manual to automated modes are reviewed. The automatic methods have several remarkable advantages such as high sample throughput, reproducibility, sensitivity, and extraction efficiency. These methods include solid-phase extraction, pipette tip micro-solid phase extraction, microextraction by packed sorbent, in-tip solid phase microextraction, in-tube solid phase microextraction, lab-on-a-chip, and lab-on-a-valve. The recent application of these methods for the extraction of organic and inorganic compounds are discussed. Also, the combination of novel technologies (3D printing and robotic platforms) with the (semi)automated methods are investigated as the future trend.

Modern automated microextraction procedures for bioanalytical, environmental, and food analyses

Sample preparation frequently is considered the most critical stage of the analytical workflow. It affects the analytical throughput and costs; moreover, it is the primary source of error and possible sample contamination. To increase efficiency, productivity, and reliability, while minimizing costs and environmental impacts, miniaturization and automation of sample preparation are necessary. Nowadays, several types of liquid-phase and solid-phase microextractions are available, as well as different automatization strategies. Thus, this review summarizes recent developments in automated microextractions coupled with liquid chromatography, from 2016 to 2022. Therefore, outstanding technologies and their main outcomes, as well as miniaturization and automation of sample preparation, are critically analyzed. Focus is given to main microextraction automation strategies, such as flow techniques, robotic systems, and column-switching approaches, reviewing their applications to the determination of small organic molecules in biological, environmental, and food/beverage samples.

Online hyphenation of in-capillary aptamer-functionalized solid-phase microextraction and extraction nanoelectrospray ionization for miniature mass spectrometry analysis

Direct mass spectrometry (MS) analysis is vital to chemical and biological investigations. However, measuring complex samples is challenging due to matrix interference, resulting in compromised MS performance. In this study, an integrated experimental protocol has been developed, combining in-capillary aptamer-functionalized solid-phase microextraction (SPME), extraction nanoelectrospray ionization (nanoESI), and miniature MS analysis. The established method was applied to analyze caffeine in electronic cigarette liquid and beverage samples as proof-of-concept demonstrations. A custom SPME strip fabricated with caffeine-binding aptamers was prepared with an immobilization density of up to 0.812 nmol cm^-2. Critical parameters affecting the effects of extraction, desorption, and ionization were optimized. A novel transition ion ratio-based strategy with enhanced quantitation accuracy was developed. The analytical performance of the proposed method was evaluated under optimized conditions. Acceptable recoveries of 87.5-111.5% with relative standard deviations of 3.1-6.1% and satisfactory sensitivity with limits of detection of 1.5 and 3 ng mL^-1 and limits of quantitation of 5 and 10 ng mL^-1 were obtained, respectively. The developed approach demonstrates a promising potential for rapid on-site applications with appealing analytical performance and efficiency.

Microbial Metabolites as Ligands to Xenobiotic Receptors: Chemical Mimicry as Potential Drugs of the Future

Xenobiotic receptors, such as the pregnane X receptor, regulate multiple host physiologic pathways including xenobiotic metabolism, certain aspects of cellular metabolism, and innate immunity. These ligand-dependent nuclear factors regulate gene expression via genomic recognition of specific promoters and transcriptional activation of the gene. Natural or endogenous ligands are not commonly associated with this class of receptors; however, since these receptors are expressed in a cell-type specific manner in the liver and intestines, there has been significant recent effort to characterize microbially derived metabolites as ligands for these receptors. In general, these metabolites are thought to be weak micromolar affinity ligands. This journal anniversary minireview focuses on recent efforts to derive potentially nontoxic microbial metabolite chemical mimics that could one day be developed as drugs combating xenobiotic receptor-modifying pathophysiology. The review will include our perspective on the field and recommend certain directions for future research. SIGNIFICANCE STATEMENT: Xenobiotic receptors (XRs) regulate host drug metabolism, cellular metabolism, and immunity. Their presence in host intestines allows them to function not only as xenosensors but also as a response to the complex metabolic environment present in the intestines. Specifically, this review focuses on describing microbial metabolite-XR interactions and the translation of these findings toward discovery of novel chemical mimics as potential drugs of the future for diseases such as inflammatory bowel disease.

Sampling Volatile Organic Compound Emissions from Consumer Products: A Review

Volatile organic compounds (VOCs) are common constituents of many consumer products. Although many VOCs are generally considered harmless at low concentrations, some compound classes represent substances of concern in relation to human (inhalation) exposure and can elicit adverse health effects, especially when concentrations build up, such as in indoor settings. Determining VOC emissions from consumer products, such as toys, utensils or decorative articles, is of utmost importance to enable the assessment of inhalation exposure under real-world scenarios with respect to consumer safety. Due to the diverse sizes and shapes of such products, as well as their differing uses, a one-size-fits-all approach for measuring VOC emissions is not possible, thus, sampling procedures must be chosen carefully to best suit the sample under investigation. This review outlines the different sampling approaches for characterizing VOC emissions from consumer products, including headspace and emission test chamber methods. The advantages and disadvantages of each sampling technique are discussed in relation to their time and cost efficiency, as well as their suitability to realistically assess VOC inhalation exposures.

Microextraction of organophosphorus pesticides on a screw coated with PAN/calcined ZnMgAl-LDH electrospun nanofibers

The present research is an attempt to expand the recently reported microextraction on screw method. For this purpose, polyacrylonitrile/calcined ZnMgAl-LDH nanofiber was fabricated by the electrospinning technique on the surface of a screw. It was applied to the extraction of organophosphorus pesticides (OPP) from agricultural samples. The separation and determination of OPPs were carried out by gas chromatography-mass spectrometry. The characterization of the fabricated nanofiber was performed utilizing Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction instruments. Effective parameters on the extraction efficiency of the analytes including sample pH, ionic strength, sample flow rate and number of cycles, type, volume, and flow rate of desorption solvent were optimized by one-variable-at-a-time method. Under optimized conditions, the limits of detection were 0.03 and 0.07 μg L^-1 for diazinon and chlorpyrifos, respectively. This method showed wide linearity in the range 0.10-1000 μg L^-1 for diazinon and 0.25-1000 μg L^-1 for chlorpyrifos with R² > 0.996. The intra- and inter-day precisions (RSD%, n = 3) were ≤ 6.4% and ≤ 7.7%, respectively. Also, RSD% values less than 11.1% were obtained for screw-to-screw reproducibility. The applicability of the method for the extraction and determination of the analytes in complex agricultural environments such as cabbage, potato, tomato, cucumber, and beetroot was investigated. The results led to acceptable relative recoveries in the range 81.0-108.2%.

Recent applications of organic molecule-based framework porous materials in solid-phase microextraction for pharmaceutical analysis

Sample preparation is an indispensable part of detection of complex samples in pharmaceutical analysis. Solid-phase microextraction (SPME) has obtained a lot of attention due to its advantages of time saving, less solvent and easily automation. A variety of functional materials are used as sorbents in SPME to carry out selective and high extraction. This review centers around the recent applications of organic molecule-based framework porous materials, such as metal organic frameworks (MOFs) and covalent organic frameworks (COFs), as SPME coating materials mainly focus on pharmaceutical analysis in food, environment, and biological samples. Four representative extraction devices are introduced, including on-fiber SPME, in-tube SPME, thin film SPME, stir bar SPME. The application prospect of other organic porous materials as sorbents for pharmaceutical analysis are also discussed, such as hyper crosslinked polymers (HCPs) and conjugated microporous polymers (CMPs). The progresses and discusses are provided to offer references for further research focusing on application and development of organic molecule-based framework porous materials in the field of SPME.

Mussel Inspired Polydopamine as Silica Fibers Coating for Solid-Phase Microextraction

Commercial solid-phase microextraction fibers are available in a limited number of expensive coatings, which often contain environmentally harmful substances. Consequently, several different approaches have been used in the attempt to develop new sorbents that should possess intrinsic characteristics such as duration, selectivity, stability, and eco-friendliness. Herein we reported a straightforward, green, and easy coating method of silica fibers for solid-phase microextraction with polydopamine (PDA), an adhesive, biocompatible organic polymer that is easily produced by oxidative polymerization of dopamine in mild basic aqueous conditions. After FT-ATR and SEM characterization, the PDA fibers were tested via chromatographic analyses performed on UHPLC system using biphenyl and benzo(a)pyrene as model compounds, and their performances were compared with those of some commercial fibers. The new PDA fiber was finally used for the determination of selected PAHs in soot samples and the results compared with those obtained using the commercial PA fiber. Good reproducibility, extraction stability, and linearity were obtained using the PDA coating, which proved to be a very promising new material for SPME.

Ionic Liquid-Assisted DLLME and SPME for the Determination of Contaminants in Food Samples

Developing effective and green methods for food analysis and separation has become an urgent issue regarding the ever-increasing concern of food quality and safety. Ionic liquids (ILs) are a new chemical medium and soft functional material developed under the framework of green chemistry and possess many unique properties, such as low melting points, low-to-negligible vapor pressures, excellent solubility, structural designability and high thermal stability. Combining ILs with extraction techniques not only takes advantage of ILs but also overcomes the disadvantages of traditional extraction methods. This subject has attracted intensive research efforts recently. Here, we present a brief review of the current research status and latest developments regarding the application of IL-assisted microextraction, including dispersive liquid–liquid microextraction (DLLME) and solid-phase microextraction (SPME), in food analysis and separation. The practical applications of ILs in determining toxic and harmful substances in food specimens with quite different natures are summarized and discussed. The critical function of ILs and the advantages of IL-based microextraction techniques over conventional extraction techniques are discussed in detail. Additionally, the recovery of ILs using different approaches is also presented to comply with green analytical chemistry requirements.

Lotus-like Ni@NiO nanoparticles embedded porous carbon derived from MOF-74/cellulose nanocrystal hybrids as solid phase microextraction coating for ultrasensitive determination of chlorobenzenes from water

Lotus-like Ni@NiO embedded porous carbons (Ni@NiO/PCs) were fabricated by pyrolysis of MOF-74/cellulose nanocrystal hybrids, and used as a solid phase microextraction (SPME) coating for ultrasensitive determination of chlorobenzenes (CBs) from water combined with gas chromatography-mass spectrometry. Owing to its abundant chemical groups, high porosity, and excellent thermal stability, the as-prepared Ni@NiO/PCs presented superior extraction performance compared to commercial SPME coatings. Notably, Ni@NiO/PCs derived from MOF-74/CNC hybrids presented higher extraction efficiencies towards CBs than that derived from pristine CNC and MOF-74 due to the formation of micro/mesopores and more abundant oxygen-containing groups. Under the optimum extraction conditions, the proposed analytical method presented wide linearity range (0.5-1500 ng L^-1), ultra-low detection of limit (0.005-0.049 ng L^-1), and excellent precision with relative standard deviations of 4.7-9.2% for a single fiber and 8.8-10.9% for 5 fibers, and long lifetime (≥160 times). The proposed analytical method was finally applied for determination of CBs from real water samples, and the recoveries were in the range of 93.2-116.8% towards eight CBs. This study delivered a novel and efficient sorbent as SPME coating to extraction and determination of CBs from water.

Comparison of Extraction Techniques for the Determination of Volatile Organic Compounds in Liverwort Samples

This article focuses on the comparison of four popular techniques for the extraction of volatile organic compounds (VOCs) from liverworts of the Calypogeia azurea species. Since extraction is the most important step in the sample analysis of ingredients present in botanical preparations, their strengths, and weaknesses are discussed. In order to determine the VOCs present in plants, selecting the appropriate one is a key step of the extraction technique. Extraction should ensure the isolation of all components present in the oily bodies of Calypogeia azurea without the formation of any artifacts during treatment. The best extraction method should yield the determined compounds in detectable amounts. Hydrodistillation (HD), applying Deryng apparatus and solid-liquid extraction (SLE), microwave-assisted extraction (MAE), and headspace solid-phase microextraction (HS-SPME) were used for volatile extraction. The extracts obtained were analysed by gas chromatography coupled to mass spectrometry (GC-MS) to determine the compounds.

Deep Eutectic Solvent-Based Coating Sorbent for Preconcentration of Formaldehyde by Thin-Film Solid-Phase Microextraction Technique

A thin-film solid-phase microextraction method with a sorbent composed of a deep eutectic solvent was developed for the preconcentration of formaldehyde from river and lake water samples. Four new deep eutectic solvents (DESs) were synthesized, each in molar ratios 1:1, 1:2, and 1:3. Among prepared compounds, the greatest efficiency in the proposed method of preconcentration of formaldehyde derivatized with Nash reagent was demonstrated by DES-3 consisting of benzyldimethylhexadecylammonium chloride and lauric acid, in a molar ratio of 1:3. For the proposed method, the parameters affecting the extraction efficiency of formaldehyde were optimized (including the choice of DES-based sorbent and desorption solvent as well as the sample volume and pH, the salting-out effect, the extraction time, and the desorption time). Under optimal conditions, the proposed method achieved good precision between 3.3% (for single sorbent) and 4.8% (for sorbent-to-sorbent) as well as good recovery ranging from 78.0 to 99.1%. The limits of detection and quantitation were 0.15 ng mL−1 and 0.50 ng mL−1, respectively. The enrichment factor was equal to 178. The developed method was successfully applied to determine formaldehyde in environmental water samples.

Development of novel thin-film solid-phase microextraction materials based on deep eutectic solvents for preconcentration of trace amounts of parabens in surface waters

A green and sensitive thin-film solid-phase microextraction method based on deep eutectic solvent was developed that enables simultaneous isolation, preconcentration, and determination of parabens in surface waters. Six new deep eutectic solvents were synthesized and used directly to prepare thin-film coatings on a stainless steel mesh support. Among the compounds obtained, the highest efficiency in the extraction of parabens was found for a material consisting of trihexyltetradecylphosphonium chloride and n-docosanol in a molar ratio of 1:2. For the proposed method, parameters affecting the extraction efficiency of parabens, such as the coating material, the desorption solvent, the volume of the sample, the pH of the sample, the extraction and desorption time, and the salting-out effect, were optimized. Under optimal conditions, the proposed method allowed us to achieve good precision between 3.6 and 6.5% and recovery ranging from 68.1 to 91.4%. The limits of detection range from 0.018 to 0.055 ng mL^-1 . This article is protected by copyright. All rights reserved.

Green analytical chemistry metrics: A review

Green analytical chemistry encourages reducing the use of toxic chemicals/reagents, using energy-efficient equipment, and generating minimal waste. The recent trends in analytical method development focus on the miniaturization of the sample preparation devices, the development of solventless or solvent-minimized extraction techniques, and the utilization of less toxic solvents. The twelve principles of GAC serve as a basic guideline for inducing greenness in the analytical procedures. Despite these guidelines, in many conditions, some undesired steps are unavoidable. Therefore, it is important to evaluate the greenness of analytical procedures to assess and, if possible, reduce their impact on the environment and workers. Several metrics have been developed for the evaluation of the greenness of analytical procedures. Analytical Eco-Scale, Green Analytical Procedure Index, and Analytical Greenness Metric are among some important tools for assessing the greenness of analytical procedures. All these metrics take different aspects of the analytical procedure into account to provide the green index of the procedure. This review covered these metrics, their principles, and examples of their application to selected analytical procedures. The advantages and limitations of these metrics with the perspective of common reader/user are presented. We believe that this paper will inspire many new perspectives and developments in this area.

Modifying current thin-film microextraction (TFME) solutions for analyzing prohibited substances: Evaluating new coatings using liquid chromatography

For identifying and quantifying prohibited substances, solid-phase microextraction (SPME) continues to arouse interest as a sample preparation method. However, the practical implementation of this method in routine laboratory testing is currently hindered by the limited number of coatings compatible with the ubiquitous high-performance liquid chromatography (HPLC) systems. Only octadecyl (C₁₈) and polydimethylsiloxane/divinylbenzene ligands are currently marketed for this purpose. To address this situation, the present study evaluated 12 HPLC-compatible coatings, including several chemistries not currently used in this application. The stationary phases of SPME devices in the geometry of thin film-coated blades were prepared by applying silica particles bonded with various functional ligands (C₁₈, octyl, phenyl-hexyl, 3-cyanopropyl, benzenesulfonic acid, and selected combinations of these), as well as unbonded silica, to a metal support. Most of these chemistries have not been previously used as microextraction coatings. The 48 most commonly misused substances were selected to assess the extraction efficacy of each coating, and eight desorption solvent compositions were used to optimize the desorption conditions. All samples were analyzed using an HPLC system coupled with triple quadrupole tandem mass spectrometry. This evaluation enables selection of the best-performing coatings for quantifying prohibited substances and investigates the relationship between extraction efficacy and the physicochemical characteristics of the analytes. Ultimately, using the most suitable coatings is essential for trace-level analysis of chemically diverse prohibited substances.

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12 HPLC-compatible TFME coatings were evaluated for extraction of small molecules.

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8 desorption solvent compositions were used to optimize the desorption conditions.

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48 prohibited substances (drugs of abuse and doping agents) were used as analytes.

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A mixed coating comprising octyl/3-cyanopropyl (50/50) provided the best results.

Novel solid-phase microextraction fiber coatings: A review

The materials used for the fabrication of solid-phase microextraction fiber coatings in the past five years are summarized in the current review, including carbon, metal-organic frameworks, covalent organic frameworks, aerogel, polymer, ionic liquids/poly (ionic liquids), metal oxides, and natural materials. The preparation approaches of different coatings, such as sol-gel technique, in-situ growth, electrodeposition, and glue methods, are briefly reviewed together with the evolution of the supporting substrates. In addition, the limitations of the current coatings and the future development directions of solid-phase microextraction are presented.

High-efficiency solid-phase microextraction performance of polypyrrole enhanced titania nanoparticles for sensitive determination of polar chlorophenols and triclosan in environmental water samples

In this work, a polypyrrole (PPy)/TiO₂ nanocomposite coating was fabricated by the direct electropolymerization of pyrrole on annealed TiO₂ nanoparticles and evaluated as a novel direct immersion solid phase microextraction (DI-SPME) fiber coating for extraction of trace amounts of pollutants in environmental water samples. The functionalized fiber is mechanically and chemically stable, and can be easily prepared in a highly reproducible manner. The effects of the pyrrole monomer concentration, polymerization voltage and polymerization time on the fiber were discussed. Surface morphological and compositional analyses revealed that the composite coating of nano polypyrrole and titanium dioxide nanoparticles (TiO₂NP_s) uniformly doped the Ti substrate. The as-fabricated fiber exhibited good extraction capability for phenolic compounds in combination with high performance liquid chromatography-UV detection (HPLC-UV). At the optimum SPME conditions, the calibration curves were linear (R² ≥ 0.9965). LODs and LOQs of less than 0.026 μg L⁻¹ and 0.09 μg L⁻¹ , respectively, were achieved, and RSDs were in the range 3.5–7.2%. The results obtained in this work suggest that PPy/TiO₂ is a promising coating material for future applications of SPME and related sample preparation techniques.

A PPy/TiO₂ nanocomposite coating was fabricated by direct electropolymerization of pyrrole on annealed TiO₂ nanoparticles and evaluated as a novel direct immersion solid phase microextraction fiber coating for the extraction of trace pollutants in water.

Automatic and renewable micro-solid-phase extraction based on bead injection lab-on-valve system for determination of tranexamic acid in urine by UHPLC coupled with tandem mass spectrometry

An automatic micro-solid-phase extraction (μSPE) method using on-line renewable sorbent beads followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was established for the determination of tranexamic acid (TXA) in urine. The μSPE method was based on the bead injection (BI) concept combined with the mesofluidic lab-on-valve (LOV) platform. All steps of the μSPE-BI-LOV were implemented by computer programming, rendering enhanced precision on time and flow events. Several parameters, including the type of sorbent, volume and composition of the conditioning solution, washing solution, and eluent composition, were evaluated to improve the extraction efficiency. The best results were obtained with a hydrophilic-lipophilic balanced mixed-mode sorbent, decorated with sulfonic acid groups (Oasis MCX), and 99% acetonitrile-water (50:50, v/v)-1% ammonium hydroxide as eluent. Chromatographic separation was performed using a BEH amide column coupled to MS/MS detection in positive ionization mode. Good linearity was achieved (R² > 0.998) for TXA concentrations in urine ranging from 300 to 3000 ng mL^-1, with LOD and LOQ of 30 and 65 ng mL^-1, respectively. Dilution integrity was observed for dilution factors up to 20,000 times, providing the extension of the upper limit of quantification to 12 mg mL^-1. The method was validated according to international guidelines and successfully applied to urine samples collected during scoliosis surgery of pediatric patients treated with TXA.

Self-rotating stir mesh screen sorptive extraction for analyzing chlorpyrifos by ion mobility spectrometry

A mesh screen was electrochemically coated with polypyrrole and used as a sorptive extractor device, for the first time. This configuration acts in such a way that it is self-rotating in the presence of a magnetic force and can be used for extraction and concentration of analytes. Actually, applying a mesh screen instead of a bar or plate in sorptive extraction provided a more effective contact area between the sorptive materials and sample solution, resulting in higher sorption efficiency. The device performance was assessed by using chlorpyrifos pesticide as a model analyte. A thermal desorption unit was coupled to an ion mobility spectrometer and applied for evaporating the extracted analyte. Different parameters affecting the extraction efficiency during the electro-polymerization and the extraction process, including the time of electrodeposition, the concentration of pyrrole, oxalic acid and salt, temperature and time of extraction, and the stirring rate of the extractor device were investigated and optimized, simultaneously. The detection and quantification limits of the method were calculated to be 0.035 and 0.1 μg L^-1, respectively. The linear dynamic range obtained was from 0.1 to 20 μg L^-1, with a determination coefficient of 0.9984. The intra-day and inter-day-relative standard deviations (RSD, n = 3) were lower than 3% and 8%, respectively. Under the optimal conditions, the absolute recovery and the enrichment factor were found to be 97% and 5820, respectively. Finally, the relative recoveries of the proposed method were calculated to be in the range of 86-111% for spiked water, wastewater, and apple samples. The results obtained from the method were validated by EPA method 622.

Nitrogen-doped porous biochar derived from marine algae for efficient solid-phase microextraction of chlorobenzenes from aqueous solution

Nitrogen-doped porous biochar (NPB) with a large specific surface area, wide pore size distribution, graphitized structure, nitrogen doping, and hydrophobicity was fabricated by high-temperature modification of algal biochar with potassium carbonate. This NPB was then uniformly coated on stainless steel wire as a novel solid-phase microextraction (SPME) fiber. The extraction efficiency of NPB-coated fiber for seven chlorobenzenes (CBs) was excellent; it was 1.0-112.2 times higher than that of commercial SPME fibers. A trace determination method was developed for seven CBs in water with the optimized extraction conditions by NPB-coated fiber and gas chromatography-electron capture detector, which showed wide linear ranges (1-1000 ng L^-1), low detection limits (0.007-0.079 ng L^-1), great repeatability (2.5-6.5% for intra-day, and 3.1-6.8% for inter-day), and excellent reproducibility (3.5-6.3%, n = 5). The practicality of the developed method was evaluated using real water samples and showed great recoveries (89.55-105.19%). This study showed that low-cost biomass wastes could be converted to advanced biochar materials by a facile method, and displayed excellent performance in SPME applications.

Assessment of commercial porous polyethylene frit for extraction of polycyclic aromatic hydrocarbons from water

Exploring commercial and inexpensive sorbents for extraction of organic pollutants is still an active area of research. Ultrahigh molecular weight polyethylene sieve plate (UMPESP) is a commercially available, low-cost, and porous frit, which has been widely used in solid-phase extraction cartridges to fix the filling materials. In this work, UMPESP was investigated for the extraction of polycyclic aromatic hydrocarbons (PAHs) from water samples. The desorption and sorption efficiencies of UMPESP were first evaluated and compared with two previously reported sorbents, low-density polyethylene plastic pellet (LDPEP) and silicone rod (SR). The comparative results showed that quantitative desorption of analytes from UMPESP, which could be easily achieved with 2 × 1.5 mL n-hexane, was more effective than that of LDPEP (>6 × 1.5 mL n-hexane) and comparable to that of SR. Additionally, shorter equilibrium time was rendered by UMPESP (shaking for 120 min) compared with SR (>480 min), due to the porous structure and larger surface area of the former. Different parameters that affect the extraction efficiency, including organic modifier, ionic strength, and pH value, were then studied. The optimized method coupled with gas chromatography-mass spectrometry afforded good linearity in a concentration range of 10-5000 ng L^-1 (except acenaphthene in the range of 25-5000 ng L^-1) with coefficients of determination ranging from 0.9957 to 0.9995 and relative standard deviations below 13.8%. The limits of detection and quantification were 0.04-3.35 ng L^-1 and 0.13-11.16 ng L^-1, respectively. Finally, the method was successfully applied to determine PAHs in real water samples, and the results showed no statistically significant difference with the concentrations derived from liquid-liquid extraction.

Recent Applications of Solid Phase Microextraction Coupled to Liquid Chromatography

Solid phase microextraction (SPME) is one of the most popular sample preparation methods which can be applied to organic compounds allowing the simultaneous extraction and pre-concentration of analytes from the sample matrix. It is based on the partitioning of the analyte between the extracting phase, generally immobilized on a fiber substrate, and the matrix (water, air, etc.), and has numerous advantages such as rapidity, simplicity, low cost, ease of use and automation, and absence of toxic solvents. Fiber SPME has been widely used in combination with various analytical instrumentation even if most of the work has been done coupling the extraction technique with gas and liquid chromatography (GC and LC). This manuscript presents an overview of the recent works (from 2010 to date) of solid phase microextraction coupled to liquid chromatography (SPME-LC) relevant to analytical applications performed using commercially available fibers or lab-made fibers already developed in previous papers, and to improved instrumental systems and approaches.

Advances and applications of in-tube solid-phase microextraction for analysis of proteins

In-tube solid-phase microextraction (IT-SPME) with capillary column as extraction device is a well-established green extraction technique with a lot of applications in the fields of biomedicine, food and environment. This article reviews the research contributions of IT-SPME for analysis of proteins. The paper first briefly describes the history of IT-SPME. Then, the development and principle of IT-SPME for analysis of proteins are introduced, in which capillary column configurations of IT-SPME and instruments for quantitative analysis of proteins are summarized. Subsequently, the synthesis strategy and recognition principle of different recognition units, including antibodies, aptamers, molecularly imprinted polymers, and boronate affinity materials, are discussed in detail. This part also introduces several rare recognition units, including lectins, restricted access materials, lysine modified with β-cyclodextrin and cell membrane. The development trend and possible future direction of IT-SPME for analysis of proteins are mentioned.