Development of stir bar sorptive-dispersive microextraction mediated by magnetic nanoparticles and its analytical application to the determination of hydrophobic organic compounds in aqueous media

Unravelling the potential of magnetic nanoparticles: a comprehensive review of design and applications in analytical chemistry

The study of nanoparticles has emerged as a prominent research field, offering a wide range of applications across various disciplines. With their unique physical and chemical properties within the size range of 1-100 nm, nanoparticles have garnered significant attention. Among them, magnetic nanoparticles (MNPs) exemplify promising super-magnetic characteristics, especially in the 10-20 nm size range, making them ideal for swift responses to applied magnetic fields. In this comprehensive review, we focus on MNPs suitable for analytical purposes. We investigate and classify them based on their analytical applications, synthesis routes, and overall utility, providing a detailed literature summary. By exploring a diverse range of MNPs, this review offers valuable insights into their potential application in various analytical scenarios.

Coupling Miniaturized Stir Bar Sorptive Dispersive Microextraction to Needle-Based Electrospray Ionization Emitters for Mass Spectrometry: Determination of Tetrahydrocannabinol in Human Saliva as a Proof of Concept

Direct coupling of sample preparation with mass spectrometry (MS) can speed up analysis, enabling faster decision-making. In such combinations, where the analysis time is mainly defined by the extraction procedure, magnetic dispersive solid-phase extraction emerges as a relevant technique because of its rapid workflow. The dispersion and retrieval of the magnetic sorbent are typically uncoupled stages, thus reducing the potential simplicity. Stir bar sorptive dispersive microextraction (SBSDME) is a novel technique that integrates both stages into a single device. Its miniaturization (mSBSDME) makes it more portable and compatible with low-availability samples. This article reports the direct combination of mSBSDME and MS using a needle-based electrospray ionization (NESI) emitter as the interface. This combination is applied to determine tetrahydrocannabinol in saliva samples, a relevant societal problem if the global consumption rates of cannabis are considered. The coupling requires only the transference of the magnet (containing the sorbent and the isolated analyte) from the mSBSDME to the hub of a hypodermic needle, where the online elution occurs. The application of 5 kV on the needle forms an electrospray on its tip, transferring the ionized analyte to the MS inlet. The excellent performance of mSBSDME-NESI-MS/MS relies on the sensitivity (limits of detection as low as 2.25 ng mL-1), the precision (relative standard deviation lower than 15%), and the accuracy (relative recoveries ranged from 87 to 127%) obtained. According to the results, the mSBSDME-NESI-MS/MS technique promises faster and more efficient chemical analysis in MS-based applications.

Behavioral and biochemical responses of the marine polychaete Perinereis aibuhitensis to 2-ethylhexyl-4-methoxycinnamate (EHMC) exposure

2-ethylhexyl-4-methoxycinnamate (EHMC) is a commonly used UV filter, and is receiving increasing concerns due to its ubiquitous occurrence in a variety of environmental media and potential adverse effects. This study was aimed to assess the ecotoxicological potentials of EHMC on the marine polychaete Perinereis aibuhitensis. To this end, ragworms were exposed to 2, 20, 200 μg/L EHMC for 14 days and multiple toxicological endpoints were investigated. The results showed that EHMC significantly reduced burrowing rate, but did not affect AChE activity. Exposure to EHMC significantly elevated the activities of SOD and CAT and decreased the levels of lipid peroxidation. Besides, the induction of AKP activity indicated a stimulated immune response in the ragworms when exposed to high concentration of EHMC. Furthermore, the upregulated expression of caspase-8 suggested that EHMC might induce apoptosis in ragworms via the death receptor-mediated extrinsic pathway. Our findings highlight the potential environmental risks of EHMC to marine ecosystems.

Applications of deep eutectic solvents in microextraction and chromatographic separation techniques: Latest developments, challenges, and prospects

Deep eutectic solvents (DESs) have recently sparked considerable attention in a variety of scientific and technological fields. The unique properties of DESs include biodegradability, easy preparation, low cost, and tuneability, rendering them a new and prospective alternative to hazardous solvents. Analytical chemistry is one of the most appealing fields where DESs proved to be applicable in either sample preparation or chromatographic separation. This review summarizes the new horizons dedicated to the application of DESs in microextraction and chromatographic separation. The utilization of DESs in microextraction, in chromatography as mobile phase additives, and in chromatographic material preparation processes is outlined. The enhancements in chromatographic performance achieved using DESs and any potential explanations deduced from the experimental findings were primarily discussed. An additional brief discussion on DESs preparation, characterization, and properties is addressed in this work. Finally, current challenges and future trends are also presented, supplying evidence for distinct possibilities regarding new research approaches involving DESs. This review can represent a guide and stimulate further research in this field.

The environmental sources of benzophenones: Distribution, pretreatment, analysis and removal techniques

Benzophenones (BPs) have wide practical applications in real human life due to its presence in personal care products, UV-filters, drugs, food packaging bags, etc. It enters the wastewater by daily routine activities such as showering, impacting the whole aquatic system, then posing a threat to human health. Due to this fact, the monitoring and removal of BPs in the environment is quite important. In the past decade, various novel analytical and removal techniques have been developed for the determination of BPs in environmental samples including wastewater, municipal landfill leachate, sewage sludge, and aquatic plants. This review provides a critical summary and comparison of the available cutting-edge pretreatment, determination and removal techniques of BPs in environment. It also focuses on novel materials and techniques in keeping with the concept of "green chemistry", and describes on challenges associated with the analysis of BPs, removal technologies, suggesting future development strategies.

Zn and Co ferrite nanoparticles: towards the applications of sensing and adsorption studies

An important deliberation of this current work is the impending applications of bivalent transition metals doped with nano ferrites and to study their emerging properties of magnetically active ferrites, which constitute oxides of iron (different conformers most demanding γ-Fe₂O₃) and transition metal complexes of bivalent metal oxides like cobalt (Co(II)) and magnesium (Mg(II)). Fe³⁺ ions occupy tetrahedral sites; the rest of Fe³⁺ and the Co²⁺ ions occupy octahedral sites. For the synthesis, a self-propagating method of combustion at lower temperature was used. Zinc and cobalt nano ferrites are synthesized from the chemical coprecipitation method of 20 to 90 nm in average size, characterized thoroughly employing FTIR and PXRD and surface morphology studied using SEM. These results explain the existence of ferrite nanoparticles in cubic spinel. Magnetically active metal oxide nanoparticles are now commonly employed in main studies of sensing, absorption, and other properties. All studies showed the interesting results.

Dispersive Magnetic Solid-Phase Extraction as a Novelty Sample Treatment for the Determination of the Main Aflatoxins in Paprika

Dispersive magnetic solid-phase extraction (DMSPE) technique is proposed as a new sensitive and effective sample treatment method for the determination of aflatoxins in paprika samples. DMSPE was followed by ultrahigh-performance liquid chromatography and high-resolution mass spectrometry detection (UHPLC-HRMS) using a non-targeted acquisition mode for the detection of main aflatoxins (aflatoxin G1, G2, B1 and B2) and derivatives. DMSPE was based on the use of magnetic nanocomposite coated with polypyrrole (PPy) polymer and the main experimental parameters influencing the extraction efficiency in adsorption and desorption steps have been studied and optimized. Analyses were performed using 250 µL magnetic PPy nanocomposite into the sample solution, adsorbing the analytes in 30 min and desorbing them with ethyl acetate (2 mL) in 15 min. The method has been validated, obtaining quantification limits between 3.5 and 4.7 µg kg-1 and recoveries between 89.5-97.7%. The high recovery rate, wide detection range and the use for the first time of the reusable Fe3O4@PPy nanomaterial in suspension for solid food matrices, guarantee the usefulness of the method developed for adequate control of aflatoxins levels in paprika. The proposed methodology was applied for the analysis of 31 samples (conventional and organic) revealing the absence of aflatoxins in the samples.

Trace determination of tetrahydrocannabinol (THC) in cosmetic products by stir bar sorptive dispersive microextraction followed by liquid chromatography-tandem mass spectrometry

An analytical method for the determination of tetrahydrocannabinol (THC) at trace level in cosmetics is presented. As psychoactive compound, the presence of THC in consumer products should be avoided. However, it might be unintentionally present in cannabidiol-rich or hemp-based products by contamination or isomerization of cannabidiol. Due to the low concentrations expected, a sensitive and selective method is necessary for the analytical control of these products. In this sense, the presented method is based on stir bar sorptive dispersive microextraction (SBSDME) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). In this work, a magnetic composite made of CoFe₂O₄ magnetic nanoparticles embedded in a commercial reverse-phase polymer (Strata™-X-RP) was employed as magnetic sorbent material taking advantage of its affinity to the target analyte. Under the optimized conditions, the method was validated and showed good analytical features in terms of linearity (at least up to 10 ng mL^-1), limits of detection and quantification (2.2 and 7.2 ng g^-1, respectively) and repeatability (RSD <10%). Moreover, relative recoveries between 99 and 109% were obtained, showing matrix effects were negligible using deuterated THC (THC-D₃) as surrogate. This new approach was successfully applied to ten commercially-available cosmetic samples of different matrices, thus showing it is suitable for the analytical control of THC in cosmetic products. The proposed methodology overcomes some of the drawbacks of the previous works with the same purpose, such as the higher limits of detection, time-consuming procedures, and consumption of large volumes of organic solvents.

Dispersive magnetic solid-phase extraction for capsaicinoid compounds in human serum using LC-HRMS: targeted and non-targeted approaches

A new analytical method based on the use of dispersive magnetic solid-phase extraction (DMSPE) is described for the preconcentration of capsaicin (CAP), dihydrocapsaicin (DCAP), and N-vanillylnonanamide (PCAP) from human serum samples. The influence of several experimental factors affecting the adsorption (nature and amount of magnetic material, adsorption time, and pH) and desorption (nature of solvent, its volume and desorption time) steps was studied. Among seven different nanomaterials studied, the best results were obtained using magnetic multiwalled carbon nanotubes, which were characterized by means of spectrometry- and microscopy-based techniques. Analyses were performed by ultra-high-performance liquid chromatography with quadrupole-time-of-flight mass spectrometry using electrospray ionization in positive mode (UHPLC-ESI-Q-TOF-MS). The developed method was validated by obtaining several parameters, including linearity (0.3-300 μg L^-1 range), and limits of detection which were 0.1, 0.15, and 0.17 μg L^-1 for CAP, DCAP, and PCAP, respectively. The repeatability of the method, expressed as relative standard deviation (RSD, n = 7), varied from 3.4 to 11%. The serum samples were also studied through a non-targeted approach in a search for capsaicinoid metabolites and related compounds. With this objective, the fragmentation pathway of this family of compounds was initially studied and a strategy was established for the identification of novel or less studied capsaicinoid-derived compounds.

Covalent organic framework in situ grown on Fe3O4 hollow microspheres for stir bar sorptive-dispersive microextraction of triazole pesticides

Based on covalent organic framework (COF) 1,3,5-tris-(4-formylphenyl)benzene-benzidine (TFPB-BD) in situ grown on Fe₃O₄ hollow microspheres and combined with gas chromatography-flame thermionic detector, a rapid and simple stir bar sorptive-dispersive microextraction method was developed for the determination of five triazole pesticides (paclobutrazol, hexaconazole, flusilazole, propiconazole, and tebuconazole). The synthesized TFPB-BD/Fe₃O₄ microspheres were characterized by transmission electron microscope, vibrating sample magnetometer, and thermogravimetric analysis, which showed that the material has strong magnetism and higher load capacity of COF. Under optimal conditions, the extraction equilibrium could be achieved within 9 min with detection limits of 0.17-1.48 μg L^-1 (S/N = 3) and a linear range of 5-1000 μg L^-1. The developed method was applied to the determination of trace triazole pesticides in apples, pears, and cabbages with recoveries from 81 to 117%.

Transport of emerging organic ultraviolet (UV) filters in ceramic membranes: Role of polyethylene (PE) microplastics

Microplastics can be considered potential carriers of emerging organic ultraviolet (UV) filters due to their considerable adsorption capacity in wastewater treatment. The adsorption behavior of organic UV filters, which are commonly contained in personal care products to preserve the skin against UV radiation, onto polyethylene (PE) microplastics were systematically studied to investigate their combined effects. Kinetics and isotherm analyses revealed that the adsorption of four organic UV filters onto PE microplastic surfaces followed a multi-rate and a heterogeneous multi-layer pattern. Several factors including salinity, microplastic size, and dosage also influenced the adsorption efficiency due to hydrophobic interactions. A bench-scale cross-flow ceramic membrane filtration experiment was investigated to evaluate the role of PE microplastics on the retention performance of organic UV filters. The retentions for organic UV filters were 34.2%-37.8% in the non-existence of PE microplastics. Conversely, organic UV filter retentions were significantly increased up to 82.2%-97.9% when they were adsorbed onto the PE microplastics, which were almost completely retained by the ceramic membrane. Therefore, organic UV filters can likely migrate and eventually be carried by PE microplastics, thus increasing the retention of both emerging organic UV filters and microplastics prior to discharge from wastewater treatment facilities.

Magnetic Nanoparticle-Based Dispersive Solid-Phase Microextraction of Three UV Blockers Prior to Their Determination by HPLC-DAD

The need for proper handling of environmental samples is significant, owing to their environmental effects on both humans and animals, as well as their immediate surroundings. In the current study, magnetic nanoparticle-based dispersive solid-phase microextraction was combined with high-performance liquid chromatography using a diode array as the detector (HPLC-DAD) for both the separation and determination of three different UV blockers, namely octocrylene, ethylhexyl methoxycinnamate, and avobenzone. The optimum conditions for the extraction were found to be as follows: Stearic acid magnetic nanoparticles (20 mg) as the sorbent, acetonitrile (100 µL) as the eluent, as well as a sample pH of 2.50, adsorption and desorption time of 1.0 min, with a 3.0 mL sample volume. The limits of detection were as low as 0.05 µg mL-1. The coefficient of determination (R2) was above 0.9950, while the percentages of relative recoveries (%RR) were between 81.2 and 112% for the three UV blockers from the environmental water samples and sunscreen products.

Stir bar sorptive-dispersive microextraction by a poly(methacrylic acid-co-ethylene glycol dimethacrylate)-based magnetic sorbent for the determination of tricyclic antidepressants and their main active metabolites in human urine

A poly(methacrylic acid-co-ethylene glycol dimethacrylate)-based magnetic sorbent was used for the rapid and sensitive determination of tricyclic antidepressants and their main active metabolites in human urine. This material was characterized by magnetism measurements, zeta potential, scanning electron microscopy, nitrogen adsorption-desorption isotherms, and thermogravimetric analysis. The proposed analytical method is based on stir bar sorptive-dispersive microextraction (SBSDME) followed by liquid chromatography-tandem mass spectrometry. The main parameters involved in the extraction step were optimized by using the response surface methodology as a multivariate optimization method, whereas a univariate approach was employed to study the desorption parameters. Under the optimized conditions, the proposed method was properly validated showing good linearity (at least up to 50 ng mL-1) and enrichment factors (13-22), limits of detection and quantification in the low ng L-1 range (1.4-7.0 ng L-1), and good intra- and inter-day repeatability (relative standard deviations below 15%). Matrix effects were observed for the direct analysis of urine samples, but they were negligible when a 1:1 v/v dilution with deionized water was performed. Finally, the method was successfully applied to human urine samples from three volunteers, one of them consuming a prescribed drug for depression that tested positive for clomipramine and its main active metabolite. Quantitative relative recoveries (80-113%) were obtained by external calibration. The present work expands the applicability of the SBSDME to new analytes and new types of magnetic sorbents.

A Study on the Applicability of NiFe2O4 Nanoparticles as the Basis of Catalysts for the Purification of Aqueous Media from Pollutants

The aim of this work is to evaluate the application of NiFe2O4 nanoparticles with spinel structures as the basis of catalysts for the purification of aqueous media from pollutants such as manganese and arsenic. The interest in these catalysts is due to their ease of production and high absorption efficiency, which, together with their magnetic properties, allow the use of nanoparticles for a long time. The sol–gel method, followed by thermal annealing of the samples at different temperatures, was proposed as a method for the synthesis of spinel nanoparticles. The choice of the annealing temperature range of 200–1000 °C is caused by the possibility of estimating changes in the structural properties and the degree of nanoparticles crystallinity. During the study of structural changes in nanoparticles depending on the annealing temperature, it was found that in the temperature range of 200–800 °C, there is an ordering of structural parameters, while for samples obtained at annealing temperatures above 800 °C, there is a partial disorder caused by the agglomeration of nanoparticles with a subsequent increase in their size. According to the results of the studies on the purification of aqueous media from pollutants, it was found that the greatest absorption efficiency belongs to nanoparticles annealed at 500–700 °C, with the purification efficiency of 70–85%, depending on the type of pollutant. The results obtained from the use of nanoparticles as catalysts for the purification of aqueous media show great prospects for their further application on an industrial scale.

A paper-based polystyrene/nylon Janus platform for the microextraction of UV filters in water samples as proof-of-concept

A new mix-mode cellulose-based sorptive phase is described that combines two different polymeric domains (i.e., nylon and polystyrene), thus providing simultaneous hydrophilic and hydrophobic features as a result. By analogy with Janus materials, the new paper-based sorptive phase has been named paper-based polystyrene/nylon Janus-platform (P-Ps/Ny-JP). The main advantages of the proposed P-Ps/Ny-JP are the sustainability, simplicity in synthesis, and low cost of this extraction device. The main parameters affecting the synthesis (i.e., coating procedure and polymers proportion) have been studied, and the resulting material has been characterized via scanning electron microscopy and infrared spectroscopy. As a proof-of-concept, the simultaneous extraction of fourteen UV filters of a wide range of polarity, with log P values ranging from - 0.234 to 16.129, from water samples and their determination by liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been performed. The proposed methodology enables the determination of these chemicals with limits of detection from 12 to 71 ng L^-1, and the precision, expressed as a relative standard deviation, was below 15%. The extraction device was applied to the analysis of real water samples likely to contain UV filters (i.e., two private swimming pool water and one seawater) and the recovery values were in the range 73-121%.

MIL-101(Fe)-derived magnetic porous carbon as sorbent for stir bar sorptive-dispersive microextraction of sulfonamides

Using MIL-101(Fe) as the source of carbon and Fe, a magnetic porous carbon (MPC) material with Fe₃C nanoparticles encapsulated in porous carbon was prepared through one-pot pyrolysis under N₂ atmosphere. With MPC as adsorption material, a stir bar sorptive-dispersive microextraction (SBSDME) method was proposed to extract and preconcentrate sulfonamides (SAs) prior to HPLC-DAD determination. To investigate their extraction ability, different MPC materials were prepared under different carbonization temperatures (600, 700, 800, 900, and 1000 °C). The material prepared under 900 °C (MPC-900) exhibited the highest extraction ability for SAs. The as-prepared MPC materials were also characterized by Raman spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, zeta potential, and other techniques. The main parameters that affect extraction were systematically studied. Under optimal conditions, favorable linearity (R² ≥ 0.9938) and detection limits (0.02-0.04 ng mL^-1) of sulfonamides were obtained. The average recoveries for spiked milk and lake water samples ranged from 76.9 to 109% and from 75.4 to 118% with RSDs of 3.10-9.63% and 1.71-11.3%, respectively. Sulfameter and sulfisoxazole were detected in milk sample. Sulfisoxazole was detected in the lake water sample. The MPC-900 material demonstrated excellent reusability. It can be reused 24 times with peak areas having no obvious decline. The method can be applied to extract ultra-trace compounds in complex sample matrices. Schematic presentation of a stir bar sorptive-dispersive microextraction (SBSDME) by using magnetic porous carbon (MPC) composites as sorbent combined with high-performance liquid chromatography for sensitive analysis of sulfonamides in milk and lake water samples.

Analytical Extraction Methods and Sorbents' Development for Simultaneous Determination of Organophosphorus Pesticides' Residues in Food and Water Samples: A Review

Extensive use of organophosphorus pesticides in agriculture leads to adverse effects to the environment and human health. Sample preparation is compulsory to enrich target analytes prior to detection as they often exist at trace levels and this step is critical as it determines the concentration of pollutants present in samples. The selection of a suitable extraction method is of great importance. The analytical performance of the extraction methods is influenced by the selection of sorbents as sorbents play a vital role in the sensitivity and selectivity of an analytical method. To date, numerous sorbent materials have been developed to cater to the needs of selective and sensitive pesticides' detection. Comprehensive details pertaining to extraction methods, developed sorbents, and analytical performance are provided. This review intended to provide a general overview on different extraction techniques and sorbents that have been developed in the last 10 years for organophosphorus pesticides' determinations in food and water samples.

Recent Advances in Sample Preparation for Cosmetics and Personal Care Products Analysis

The use of cosmetics and personal care products is increasing worldwide. Their high matrix complexity, together with the wide range of products currently marketed under different forms imply a challenge for their analysis, most of them requiring a sample pre-treatment step before analysis. Classical sample preparation methodologies involve large amounts of organic solvents as well as multiple steps resulting in large time consumption. Therefore, in recent years, the trends have been moved towards the development of simple, sustainable, and environmentally friendly methodologies in two ways: (i) the miniaturization of conventional procedures allowing a reduction in the consumption of solvents and reagents; and (ii) the development and application of sorbent- and liquid-based microextraction technologies to obtain a high analyte enrichment, avoiding or significantly reducing the use of organic solvents. This review provides an overview of analytical methodology during the last ten years, placing special emphasis on sample preparation to analyse cosmetics and personal care products. The use of liquid–liquid and solid–liquid extraction (LLE, SLE), ultrasound-assisted extraction (UAE), solid-phase extraction (SPE), pressurized liquid extraction (PLE), matrix solid-phase extraction (MSPD), and liquid- and sorbent-based microextraction techniques will be reviewed. The most recent advances and future trends including the development of new materials and green solvents will be also addressed.

Biodegradation of 2-ethylhexyl-4-methoxycinnamate in river sediments and its impact on microbial communities

Numerous studies have evaluated the toxicity and endocrine disrupting properties of organic UV filters for aquatic organisms, but little is known about their biodegradation in river sediments and their impact on microorganisms. We have set up the sterile and microbiological systems in the laboratory, adding 2-ethylhexyl-4-methoxycinnamate (EHMC), one of organic UV filters included in the list of high yield chemicals, at concentrations of 2, 20 and 200 μg/L, and characterized the microbial community composition and diversity in sediments. Monitoring of EHMC degradation within 30 days revealed that the half-life in the microbial system (3.49 days) was much shorter than that in the sterile system (7.55 days). Two potential degradation products, 4-mercaptobenzoic acid and 3-methoxyphenol were identified in the microbial system. Furthermore, high-throughput 16s and 18s rRNA gene sequencing showed that Proteobacteria dominated the sediment bacterial assemblages followed by Chloroflexi, Acidobacteria, Bacteroidetes and Nitrospirae; Eukaryota_uncultured fungus dominated the sediment fungal assemblages. Correlation analysis demonstrated that two bacterium genera (Anaerolineaceae_uncultured and Burkholderiaceae_uncultured) were significantly correlated with the biodegradation of EHMC. These results illustrate the biodegradability of EHMC in river sediments and its potential impact on microbial communities, which can provide useful information for eliminating the pollution of organic UV filters in natural river systems and assessing their potential ecological risks.

Polydopamine-coated magnetic nanoparticles for the determination of nitro musks in environmental water samples by stir bar sorptive-dispersive microextraction

Magnetic-based microextraction approaches have gained popularity in recent years due to the magnetic properties of the extraction phases allowing to handle them easier and more efficiently. This work describes a magnetic-based analytical method for the determination of the family of nitro musks in environmental water samples. These compounds have been of great concern due to their environmental impacts and potential health effects. The method is based on stir bar sorptive-dispersive microextraction (SBSDME) as extraction approach, prior to thermal desorption coupled to gas chromatography-mass spectrometry analysis (TD-GC-MS). For this purpose, polydopamine-coated cobalt ferrite magnetic nanoparticles (CoFe₂O₄@PDA) were used as extraction material. The main parameters involved in the extraction procedure (i.e., sorbent amount, extraction time and ionic strength) as well as in the thermal desorption step (i.e., temperature and desorption time) were evaluated in order to obtain the highest sensitivity. Under the selected conditions, the method showed good linearity, limits of detection and quantification in the low ng L^-1 range, intra- and inter-day repeatability with RSD <15%, and high enrichment factors (178-640). Finally, the method was applied to four environmental water samples of different origin. Relative recovery values ranging from 91 to 120% highlighted that the matrices under consideration do not affect the extraction process. This work constitutes the first time in which nitro musks compounds were selectively extracted by taking advantage the high potential that magnetic-based microextraction techniques offer, specially SBSDME.

Determination of environmental properties and toxicity of octyl-dimethyl-para-aminobenzoic acid and its degradation products

Octyl-dimethyl-para-aminobenzoic acid (ODPABA) is one of compounds of emerging concern. It undergoes transformations under the influence of oxidizing or chlorinating agents and UV radiation forming products with different properties. There is very little experimental data concerning the environmental fate of ODPABA and its transformation products. Therefore, the purpose of the studies was to determine environmental parameters: water solubility, soil - water partition coefficient, octanol - air partition coefficient, bioconcentration factor as well as half-life in air, water and soil. Based on the results obtained, the persistence and migration possibilities of ODPABA and its transformation products in the aquatic environment were estimated. Moreover, the ecological toxicity of oxidation and chlorination products was investigated. Microtox®, Daphtoxkit F® and Artoxkit M® tests were used to determine toxicity. LC₅₀ for Fish and Daphnia magna was calculated by Ecosar module. Studies have shown that as a result of ODPABA transformations, chloroorganic products are formed, which are lipophilic, are bioconcentrated in organic matter, are characterized by significant environmental persistence, can spread over considerable distances and are toxic. Oxidation products have significantly smaller impact on the environment. They are characterized by higher water solubility, lower bioconcentration factor and are less toxic.

Cellulose-ferrite nanocomposite for monitoring enniatins and beauvericins in paprika by liquid chromatography and high-resolution mass spectrometry

Paprika is considered a high-quality product being one of the most consumed spices in the world. Contamination with mycotoxins may appear due to inappropriate practices during processing or resulting from invading mould in the final manufactured products. A sample treatment based on dispersive magnetic solid-phase extraction (DMSPE) has been proposed for emerging mycotoxin determination, enniatins (ENNs) and beauvericins (BEAs), in paprika. Different magnetic nanoparticles were tested, and cellulose-ferrite nanocomposite was selected for the extraction and preconcentration of the mycotoxins. Nanocomposite was characterised using field emission scanning electron microscopy and energy dispersive X-ray spectroscopy in terms of morphology and elemental composition. High-resolution mass spectrometry allowed the quantification of the five main emerging mycotoxins and the monitoring of unexpected members of this class of toxic fungal secondary metabolites. The method has been validated, obtaining limits of quantification between 9.5 and 9.9 μg kg^-1 and testing its trueness through recovery studies, with satisfactory values of between 89.5 and 97.7%. Relative standard deviations were calculated to evaluate the intra- and inter-day precision and values lower than 8% were obtained in all cases. The analysis of 26 samples, including conventional and organic, demonstrated the presence of ENNB1 at 12.0 ± 0.6 μg kg^-1 in one of the samples studied. Other analogues ENNs and BEAs were not detected.

Nanoparticle coatings for stir bar sorptive extraction, synthesis, characterization and application

During the last ten years, number of articles published on synthesis and applications of nano-particles (NPs) have been increased by a factor of 40. One of the most interesting applications of NPs is their using as high capacity, robust and highly selective coatings for stir bar sorption extraction (SBSE). Utilizing NPs greatly promoted applications of SBSE and has gained importance on green sample preparation. In this article, all available literature on nano-coatings as media for microextraction by stir bar is reviewed. This includes non-functionalized NPs (mostly, metallic/metallic oxide and graphene based), functionalized coatings, and decorated coatings (both mono- and multifunctional). Various applications, advantages and disadvantages of each nano-coated prepared stir bar are discussed in detail along with critical evaluation of currently available methods.

Greenness of magnetic nanomaterials in miniaturized extraction techniques: A review

Green analytical chemistry principles should be followed, as much as possible, and particularly during the development of analytical sample preparation methods. In the past few years, outstanding materials such as ionic liquids, metal-organic frameworks, carbonaceous materials, molecularly imprinted materials, and many others, have been introduced in a wide variety of miniaturized techniques in order to reduce the amount of solvents and sorbents required during the analytical sample preparation step while pursuing more efficient extraction methods. Among them, magnetic nanomaterials (MNMs) have gained special attention due to their versatile properties. Mainly, their ability to be separated from the sample matrix using an external magnetic field (thus enormously simplifying the entire process) and their easy combination with other materials, which implies the inclusion of a countless number of different functionalities, highly specific in some cases. Therefore, MNMs can be used as sorbents or as magnetic support for other materials which do not have magnetic properties, the latter permiting their combination with novel materials. The greenness of these magnetic sorbents in miniaturized extractions techniques is generally demonstrated in terms of their ease of separation and amount of sorbent required, while the nature of the material itself is left unnoticed. However, the synthesis of MNMs is not always as green as their applications, and the resulting MNMs are not always as safe as desired. Is the analytical sample preparation field ready for using green magnetic nanomaterials? This review offers an overview, from a green analytical chemistry perspective, of the current state of the use of MNMs as sorbents in microextraction strategies, their preparation, and the analytical performance offered, together with a critical discussion on where efforts should go.

Microextraction Techniques with Deep Eutectic Solvents

In this review, the ever-increasing use of deep eutectic solvents (DES) in microextraction techniques will be discussed, focusing on the reasons needed to replace conventional extraction techniques with greener approaches that follow the principles of green analytical chemistry. The properties of DES will be discussed, pinpointing their exceptional performance and analytical parameters, justifying their current extensive scientific interest. Finally, a variety of applications for commonly used microextraction techniques will be reported.

Stir bar sorptive extraction and its application

Recent progress of stir bar sorptive extraction (SBSE) in the past six years is reviewed. The preparation methods including electrodeposition, self-assembly, solvent exchange, physical magnetic adsorption and electrostatic spinning, for the coated stir bar are summarized and compared, specifically for a specific material for coatings fabrication, e.g., carbon-based materials and metal organic frameworks. The emerging materials (e.g., graphene, graphene oxide, carbon nanotubes, monolith, metal-organic frameworks and porous organic polymers) applied for coated stir bar fabrication are one of the focus of this review, along with their respective advantages in extraction process and application in trace analysis. The development and application of extraction apparatus of SBSE are also involved. Based on these information, the development status and prospects of SBSE as an efficient sample pretreatment technique in real sample analysis are discussed.

Sonodecoration of magnetic phosphonated-functionalized sporopollenin as a novel green nanocomposite for stir bar sorptive dispersive microextraction of melamine in milk and milk-based food products

The novel green magnetic phosphonated-functionalized sporopollenin nanocomposite (MPSP-nanocomposite) was synthetized and used for stir bar sorptive dispersive microextraction (SBSDME) of melamine in milk and milk-based food products. TEM, SEM-EDX, FT-IR, VSM techniques were applied for characterization of MPSP-nanocomposite. The influential parameters including pH, extraction time, stirring rate, elution solvent type and volume, sample volume, desorption time, and ionic strength were studied and at optimum conditions, the linear range of 1-500 (µg L^-1), the LOD (S/N = 3) of 0.30 (µg L^-1), and the LOQ (S/N = 10) of 0.95 (µg L^-1) were achieved. The intra-day precision values (RSD (%), n = 7) of 3.5% for the melamine concentration of 25 (µg L^-1). The relative recoveries of 95.8% to 99.6% were acquired for the real samples which confirmed that the proposed method could be successfully utilized in complex matrixes with high matrix effects.

Use of Nanomaterial-Based (Micro)Extraction Techniques for the Determination of Cosmetic-Related Compounds

The high consumer demand for cosmetic products has caused the authorities and the industry to require rigorous analytical controls to assure their safety and efficacy. Thus, the determination of prohibited compounds that could be present at trace level due to unintended causes is increasingly important. Furthermore, some cosmetic ingredients can be percutaneously absorbed, further metabolized and eventually excreted or bioaccumulated. Either the parent compound and/or their metabolites can cause adverse health effects even at trace level. Moreover, due to the increasing use of cosmetics, some of their ingredients have reached the environment, where they are accumulated causing harmful effects in the flora and fauna at trace levels. To this regard, the development of sensitive analytical methods to determine these cosmetic-related compounds either for cosmetic control, for percutaneous absorption studies or for environmental surveillance monitoring is of high interest. In this sense, (micro)extraction techniques based on nanomaterials as extraction phase have attracted attention during the last years, since they allow to reach the desired selectivity. The aim of this review is to provide a compilation of those nanomaterial-based (micro)extraction techniques for the determination of cosmetic-related compounds in cosmetic, biological and/or environmental samples spanning from the first attempt in 2010 to the present.

Reduced graphene oxide-based magnetic composite for trace determination of polycyclic aromatic hydrocarbons in cosmetics by stir bar sorptive dispersive microextraction

This work describes a sensitive and rapid analytical method for trace determination of polycyclic aromatic hydrocarbons (PAHs) in cosmetic samples. The proposed method is based on stir bar sorptive-dispersive microextraction (SBSDME). A magnetic composite made of CoFe₂O₄ magnetic nanoparticles embedded into reduced graphene oxide sheets is used as sorbent phase. After the extraction, the target analytes are desorbed in toluene and then analyzed by gas chromatography-mass spectrometry (GC-MS). The main parameters involved in the extraction procedure (i.e., composite amount, extraction time and desorption time) were evaluated and optimized to provide the best extraction efficiency. The method was successfully validated under the selected conditions, showing a linear range of at least up to 125 ng mL^-1, instrumental and method limits of detection from 0.02 to 2.50 ng mL^-1 and from 0.15 to 24.22 ng g^-1, respectively, and relative standard deviations (RSD) below 10 % for all the target analytes. Standard addition combined with internal standard calibration was employed for quantification. The proposed method was successfully applied to the analysis of ten PAHs in four cosmetic products of different matrix. Several analytes between 14 and 464 ng g^-1 were found, some of them prohibited in cosmetic products. This work expands the analytical potential of SBSDME technique to other analytes and to the use of new sorbent phases, showing the great versatility of this approach depending on the characteristics of the analytes.

Dispersive Solid-Phase Extraction using Magnetic Carbon Nanotube Composite for the Determination of Emergent Mycotoxins in Urine Samples

Dispersive magnetic solid-phase extraction (DMSPE) has received growing attention for sample treatment preconcentration prior to the separation of analytes due to its many advantages. In the present work, the potential of DMSPE for the determination of emergent mycotoxins (enniatins A, A1, B and B1, and beauvericin) is investigated for the first time. Different magnetic nanoparticles were tested and a magnetic multiwalled carbon nanotube (Fe3O4@MWCNT) composite was selected for the extraction and preconcentration of the five target mycotoxins in human urine samples before their analysis by ultrahigh performance liquid chromatography coupled to high resolution mass spectrometry (UHPLC-HRMS). The nanocomposite was characterized by energy dispersive X-ray spectrometry, scanning electron microscopy, Fourier transform infrared spectrophotometry, and X-ray diffraction. Several parameters affecting the adsorption and desorption of DMSPE steps were optimized and the method was fully validated. Due to a matrix effect, matrix-matched calibration curves were necessary to carry out quantification. In this way, limits of quantification of between 0.04 and 0.1 μg/L, relative standard deviation values lower than 12% and recoveries between 89.3% and 98.9% were obtained. Finally, a study of the reuse of the Fe3O4@MWCNT composite was carried out, confirming that it can be reused at least four times.

Fabrication of chromium-imprinted polymer: a real magneto-selective sorbent for the removal of Cr(vi) ions in real water samples

Graphical representation (a and b) show the procedure for the synthesis of Cr(vi) ion-imprinted magnetic polymer.

Fate of UV filter Ethylhexyl methoxycinnamate in rat model and human urine: Metabolism, exposure and demographic associations

Ethylhexyl methoxycinnamate (EHMC) is one of the most frequently used UV filters in sunscreens and other cosmetic products. Its ubiquitous presence in various environmental matrices and its endocrine disrupting properties have been widely reported. However, we know little about the effect of EHMC exposure on humans, mainly due to its fast metabolism. In this study, urine and plasma of EHMC-dosed rats were analysed to identify its major metabolites. Five metabolites were found, with four firstly reported. Two metabolites were putatively identified as 4-methoxycinnamic acid (4-MCA) and 4'-methoxyacetophenone (4'-MAP). Quantitative results revealed that their excretion concentrations were much higher than the parent compound. Because of these high concentrations, for the human biomonitoring study, EHMC and these two metabolites were detected simultaneously in urine samples from Chinese children and adolescents. The results indicated wide exposure to EHMC, 4-MCA and 4'-MAP. The correlation between urinary concentration of EHMC and 4-MCA as well as 4-MCA and 4'-MAP provided important clues as to the sources and metabolic pathways among these three compounds. Several demographic factors were also assessed with the exposure level. As the first human exposure study of EHMC in a Chinese population, this report would help to establish an exposure database facilitating health risk assessment of EHMC.

Magnetic molecularly imprinted polymers for the detection of aminopyralid in milk using dispersive solid-phase extraction

A method for dummy molecular imprinting-magnetic dispersive solid-phase extraction (MI-MDSPE) coupled with liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed for the selective determination of aminopyralid in milk. The magnetic material and polymers were combined via a series of modifications in Fe3O4. Fe3O4@SiO2-NH2@MIP, Fe3O4@SiO2-COOH@MIP and two types of aminopyralid-specific magnetic molecularly imprinted polymers (MMIPs) were prepared on the surface of magnetic nanoparticles modified with amino and carboxyl groups. The morphology and magnetic properties of the polymer were characterized. Fe3O4@SiO2-NH2@MIP exhibits not only good dispersibility and magnetic properties, but also an outstanding recognition pattern to the target analyte. Adsorption experiments demonstrated that Fe3O4@SiO2-NH2@MIP, with a high specific surface area and fast mass transfer rate, had a higher affinity than Fe3O4@SiO2-COOH@MIP towards aminopyralid. Under the optimized MI-MDSPE conditions, the method had good linearity (R 2 > 0.9972), excellent recoveries (83.3-90%), and good precision (relative standard deviations (RSDs) < 12.6%). This method has limits of detection (LOD) and quantification (LOQ) of 0.231 and 0.77 μg kg-1, respectively, indicating that these MMIPs can be used to analyse trace levels of aminopyralid in real samples.

Novel sample preparation approaches in gas chromatographic analysis: Promising ideas

The development of sample preparation procedures is still a dynamic process despite a number of already proposed techniques. The main challenge in this research field is to fully replace classical procedures like liquid-liquid extraction and solid-phase extraction in gas chromatographic analysis. Some progress has been already achieved for the last 20 years when miniaturized techniques were incorporated in ISO standards. The current review is focused on novel approaches in sample treatment that appeared since 2010. It includes research studies describing non-conventional instrumental design available to inspire future progress in the field. A combination of a few extraction principles and supporting with additional treatment are the main core suggested for improvement of sample preparation efficiency. This requires good compatibility of extraction media, assessment of multiple experimental parameters, and potential automatization possibilities.