Analyte Migration Research Articles

ToF-SIMS Investigation of Environmental Effects on Analyte Migration in Matrix Coatings for Mass Spectrometry Imaging Using a Newly Developed Vapor Deposition System.

High resolution mass spectrometry images are of increasing importance in biological applications, such as the study of tissues and single cells. Two promising techniques for this are matrix-enhanced secondary ion mass spectrometry (ME-SIMS) and matrix-assisted laser desorption/ionization (MALDI). For both techniques, the sample of interest must be coated with a matrix prior to analysis, and analytes must migrate into the matrix. The mechanisms involved in this migration and the factors that influence the migration are poorly understood, which lead to difficulties with reproducibility. In this work, a sublimation matrix coater with an effusion cell and sample cooling was developed and built in-house for controlled physical vapor deposition. In this system, sample transfer between the coater and mass spectrometer is possible without breaking vacuum, which facilitates the study of environmental influences on analyte migration. The influence of exposure to ambient air on the migration of two analytes (a lipid and a peptide), which were coated with the matrix α-cyano-4-hydroxycinnamic acid (CHCA), was studied using 3D-SIMS imaging. Although the distribution of analyte in the matrix changed very little after 21 h of storage in vacuum, significant redistribution of the analyte was observed after exposure to ambient air. The magnitude of the effect was greater for the lipid than for the peptide. Further work is needed to determine the role of humidity in the redistribution process and the impact of analyte redistribution on MALDI measurements.

What words can tell us about social determinants of mental health: A multi-method analysis of sentiment towards migration experiences and community life in Lima, Perú.

To support resilience in contexts of migration, a deeper understanding of the experiences of both receiving communities and migrants is required. Research on the impacts of migration on community life is limited in contexts with high internal migration (i.e., migrating within one's country of origin). Evidence suggests that cultural similarity, community relationships, and access to resources may be protective factors that could be leveraged to support the mental health of internal migrants. The current study uses data drawn from a sample of pregnant Peruvian women (N = 251), 87 of whom reported being internal migrants and 164 of whom reported being from the locale of the study (Lima, Perú). The aim was to better understand the social experience of internal migration for both local and migrant women. Inductive thematic analysis was used to examine migration experience and perceived impact of migration on community life. Internal migrants discussed three themes relative to their experiences: motivations, adjustment, and challenges. Experiences of women in receiving communities consisted of four themes related to migration: positive, negative, neutral, and mixed perceptions. Linguistic Inquiry and Word Count (LIWC-22) software was also used to assess sentiment towards migration. Across both analytic methods, migration motivations and perceptions were multifaceted and migrants reported a wide range of challenges before, during, and after migration. Findings indicated that attitudes toward migration are broadly positive, and that there is a more positive appraisal of migration's impact on the community life for internal as opposed to international migration.

Switching Separation Migration Order by Switching Electrokinetic Regime in Electrokinetic Microsystems.

Analyte migration order is a major aspect in all migration-based analytical separations methods. Presented here is the manipulation of the migration order of microparticles in an insulator-based electrokinetic separation. Three distinct particle mixtures were studied: a binary mixture of particles with similar electrical charge and different sizes, and two tertiary mixtures of particles of distinct sizes. Each one of the particle mixtures was separated twice, the first separation was performed under low voltage (linear electrokinetic regime) and the second separation was performed under high voltage (nonlinear electrokinetic regime). Linear electrophoresis, which discriminates particles by charge, is the dominant electrokinetic effect in the linear regime; while nonlinear electrophoresis, which discriminates particles by size and shape, is the dominant electrokinetic effect in the nonlinear regime. The separation results obtained with the three particle mixtures illustrated that particle elution order can be changed by switching from the linear electrokinetic regime to the nonlinear electrokinetic regime. Also, in all cases, better separation performances in terms of separation resolution (Rs) were obtained by employing the nonlinear electrokinetic regime allowing nonlinear electrophoresis to be the discriminatory electrokinetic mechanism. These findings could be applied to analyze complex samples containing bioparticles of interest within the micron size range. This is the first report where particle elution order is altered in an iEK system.

Multilayer coatings based on gold nanoparticles and polymers with bovine serum albumin as a functional layer for the chiral separation in capillary electrochromatography.

In this study, we developed physically adsorbed multi-layer coatings using poly-l-lysine or poly(diallyldimethylammonium chloride) and gold nanoparticles, which were functionalized with bovine serum albumin for the chiral separation in electrochromatography. The approach involves sequentially depositing positively charged polymers and negatively charged citrate-stabilized gold nanoparticles. By repeating this modification cycle, we created two- and four-layer coatings, which were sequentially functionalized with albumin forming three- and five-layer coatings that were finally applied for the separation of enantiomers of dl-tryptophan. The formed coatings exhibit stability across a pH range of 2-10 and feature a dense, uniform surface, as confirmed by scanning electron microscope images. The number of layers impacted nanoparticle deposition density, with five-layer coatings being denser than three-layer ones. Five-layer coatings enable baseline separation of dl-tryptophan enantiomers, whereas three-layer coatings require the presence of albumin in the background electrolyte for separation. Therefore, increasing the number of layers and gold nanoparticles density enhances albumin active center concentration on capillary walls, improving the separation of dl-tryptophan enantiomers. The five-layer coatings can be easily fabricated and possess good repeatability of analytes migration time.

Detection of Triacetone Triperoxide in air combining SnO2 sensor e-nose enhanced with a kinetic model

In the domain of high-temperature semiconductor arrays for electronic noses (e-noses), Metal Oxide Sensors (MOS) have a pivotal role despite their non-linear response to chemical vapors. A prevalent approach to enhance the identification algorithm's performance involves implementing mathematical models during the MOS signal processing. However, certain models rely solely on mathematical goodness-of-fit, overlooking crucial features that render practical e-nose applications ineffective. This paper introduces a theoretical model for the qualitative analysis of MOS signals, focusing on two primary diffusion processes: analyte migration to the sensor's surface and the subsequent dispersion of some of these molecules within the MOS bulk. Additionally, this work discusses a model validation using an ad-hoc e-nose, built with SnO2 gas sensors, and six organic chemicals, detailing main data processing steps. Finally, disclosed results showcase a high success rate for Triacetone Triperoxide (TATP) identification, one of the most significant threats among homemade explosives (HME). The presented conclusions underscore the enhanced efficacy of the proposed signal model for e-nose vapors identification and its practical utility in strengthening pre-emptive HME identification to enhance public safety.

A Cost-Effective Microfluidic Device to Teach the Principles of Electrophoresis and Electroosmosis.

Electrophoresis is integral to analytical and biochemistry experiences in undergraduate education; however, fundamental principles of the method are often taught in upper-level laboratories through hands-on experiences. A laboratory activity is reported that teaches the concepts of electrophoretic mobility and electroosmotic flow. A single reuseable instrument, called a mini-E, costs 37 USD and consists of a DC power supply, a voltmeter, platinum electrodes, and a chip cast in polydimethylsiloxane. This activity uses common reagents costing only 0.02 USD per student. Experiments are devised that allow students to investigate the properties of electrophoretic flow and electroosmotic flow by separating the two commonly used food dyeing agents Brilliant Blue FCF and Allura Red AC in vinegar and in a solution of ammonium hydroxide. A dark-purple mixture of these dyes is separated into red and blue bands that are easily visualized. The migration order of the dyes differs when the separation is performed under conditions of reversed polarity and suppressed electroosmotic flow (vinegar) compared to conditions of normal polarity and active electroosmotic flow (ammonium hydroxide). When delivered to chemistry majors, students had a significant gain in their ability to apply the concepts of electroosmosis and electrophoresis to predict analyte migration. Although this activity targets upper-level chemistry content, it can also be adapted for other laboratory experiences.

Continuous Electrophoretic Separation of Charged Dyes in Liquid Foam

A novel electrophoretic separation technique is presented, where continuous electrophoretic separation is demonstrated using free flowing liquid foams. Continuous foam electrophoresis combines the principle of capillary electrophoresis and interactions between analytes and the electrical double layer, with the ability of Free Flow Electrophoresis to continuously separate and recover analytes automatically. A liquid foam is used to provide a network of deformable micro and nano channels with a high surface area, presenting a novel platform for electrophoresis, where interfacial phenomena could be exploited to modify analyte migration. The main purpose of this paper is to present a proof-of-concept study and provide fundamental understanding of a complex foam system in continuous separation mode, i.e., flowing liquid foam under an external electric field with electrophoresis and chemical reactions at the electrodes continuously changing the system. Liquid foam is generated using a mixture of anionic and non-ionic surfactants and pumped through a microfluidic separation chamber between two electrodes. The effectiveness of the device is demonstrated using a dye mixture containing a neutral dye and an anionic dye. At the outlet, the foam is separated and collected into five fractions which are individually probed for the concentration of the two dyes used. The anionic dye was concentrated up to 1.75 (±0.05) times the initial concentration in a select outlet, while the neutral dye concentration remained unchanged in all outlets, demonstrating the potential for electrophoretic foam separations.

Application of validated migration models for the risk assessment of styrene and acrylonitrile in ABS plastic toys

With styrene and acrylonitrile in ABS plastic toys as examples, this paper introduces to the development of a systematic strategy for studying the chemical migration risk in toys. The approach, included the detection method, establishment of migration model, model verification, and the practical application of the model in risk assessment. First, simple and sensitive methods for detecting analyte residues and migration were developed by headspace GC-MS. Then, the migration models were established based on the migration data from 5 min to 168 h and verified using 11 ABS samples. The results showed that the predicted values of the models and the experimental values had a good fit (RMSE=0.10–8.72 %). Subsequently, the migration of analytes in 94 ABS toys was predicted with these models at specific migration times. The daily average exposure level to styrene and acrylonitrile were estimated for children (3 months to 3 years). At last, the migration models reasonably predicted that the cancer risk of styrene and acrylonitrile in ABS toys were 1.6 × 10−8–1.4 × 10−6 and 3.1 × 10−8–1.6 × 10−6, respectively. This research contributes to promote toy safety and child health by enriching migration models and risk assessments.

Detrimental impact of aqueous mobile phases on 18F-labelled radiopharmaceutical analysis via radio-TLC.

The list of new positron-emission tomography (PET) tracers has rapidly grown in the past decade, following discoveries of new biological targets and therapeutic strategies, with several compounds garnering recent regulatory approval for clinical use. During the development of synthesis methods and production of new tracers for imaging, analytical methods for radio-high performance liquid chromatography (radio-HPLC) and radio-thin layer chromatography (radio-TLC) separations need to be developed to assess radiochemical compositions. Radio-TLC is often faster, simpler, and sometimes more accurate than radio-HPLC (as there is no underestimation of [18F]fluoride when analyzing 18F-labeled radiopharmaceuticals). Many protocols have been developed for separating 18F-radiopharmaceuticals on silica TLC plates, typically with [18F]fluoride retained at the origin and the radiopharmaceutical (and impurities) migrating along the plate. Interestingly, many reports describe the use of aqueous conditions to mobilize polar species, but it is known that aqueous conditions can modify silica and alter its chromatographic behavior. In this technical note, we explore the effects that aqueous conditions have on the analysis of 18F-radiopharmaceutical mixtures, revealing that with sufficient water, the radionuclide ([18F]fluoride) can migrate away from the origin and can be split into multiple bands. Furthermore, water can hinder the migration of the radiopharmaceutical. These effects can lead to overlapped bands or reversal of the normally expected order of bands, potentially leading to the misinterpretation of results if care is not taken to validate the TLC method carefully.

Simultaneous determination of phthalates and bisphenols from plastic bottled water samples by dispersive solid-phase extraction with multiwalled carbon nanotubes and liquid chromatography/atmospheric pressure photoionization/high-resolution mass spectrometry.

Phthalates and bisphenols were reported as endocrine disrupting chemicals and hence a potential threat to human health. Polyethylene terephthalate bottles are being used to store drinking water and the probability of migration of phthalates and bisphenols from the bottles into the water is high. The migration of analytes with respect to different storage conditions need to be studied. A sensitive analytical method for simultaneous determination of seven phthalates and three bisphenols from packaged drinking water was developed using liquid chromatography/atmospheric pressure photoionization/high-resolution mass spectrometry. The analytes were extracted by dispersive solid-phase extraction by multiwalled carbon nanotubes. The developed method showed linearity from 0.5 to 5000 μg/L with the limit of detection and limit of quantification ranging from 0.5 to 1μg/L and 1 to 2μg/L, respectively, for phthalates and bisphenols. The inter- and intraday variations were below 10%. The recoveries were in the range of 79.5% to 112%. The migration of phthalates and bisphenols increased with storage time and temperature. Maximum migration was observed for diisobutyl phthalate of 1209.7ng/L followed by dibutyl phthalate at 777.8ng/L on 180 days of analysis at room temperature. Migration of bis(2-ethylhexyl) phthalate was observed to be higher at elevated temperatures, increasing from 14.9 to 514 ng/L. Similarly, migration of bisphenol-A was increased at 45°C. The results were subjected to analysis of variance (ANOVA) studies and the results showed significant variations of phthalates and bisphenols with respect to storage temperature and time. The use of atmospheric pressure photoionization facilitated simultaneous determination of phthalates and bisphenols. The migration of phthalates and bisphenols increased with increasing temperature and storage time. Maximum migration was observed for diethyl, diisobutyl, dibutyl and bis(2-ethylhexyl) phthalates. This may be attributed to the type of plastic, the processing parameters and recycling.

Monolithic Silica Microbands Enable Thin-Layer Chromatography Analysis of Single Cells.

A picoliter thin-layer chromatography (pTLC) platform was developed for analyzing extremely miniature specimens, such as assay of the contents of a single cell of 1 picoliter volume. The pTLC chip consisted of an array of microscale bands made from highly porous monolithic silica designed to accept picoliter-scale volume samples. pTLC bands were fabricated by combining sol-gel chemistry and microfabrication technology. The width (60-80 μm) and depth (13 μm) of each band is comparable to the size of single cells and acted to reduce the lateral diffusion and confine the movement of compounds along the microbands. Ultrasmall volumes (tens of pL) of model fluorescent compounds were spotted onto the microband by a piezoelectric microdispenser and successfully separated by pTLC. The separation resolution and analyte migration were dependent on the macropore size (ranging from 0.3 to 2.3 μm), which was adjustable by changing the porogen concentration during the sol-gel process. For a 0.3 μm macropore size, attomoles of analyte were detectable by fluorescence using standard microscopy methods. The separation resolution, theoretical plate number, and separation times ranged from 1.3 to 2.1, 4 to 357, and 2 to 8 min, respectively, for the chosen model biological lipids. To demonstrate the capability of pTLC for separating analytes from single mammalian cells, cells loaded with fluorescent lipophilic dyes or sphingosine kinase reporter were spotted on microbands, and the single-cell contents separated by pTLC were detected from their fluorescence. These results demonstrate the potential of pTLC for applications in many areas where miniature specimens and high-throughput parallel analyses are needed.

Construction, application and validation of a new algorithm for determining light nonaqueous-phase liquid fluxes in unsaturated zones

An analytical algorithm coupling free-phase migration, precipitation, and natural attenuation through volatilization and biodegradation (FPVB) was developed to calculate the flux of light nonaqueous-phase liquid (LNAPL) leaking from unsaturated zone to groundwater. Sandbox and soil column experiments were performed to identify the LNAPL migration characteristics and states to provide data to establish and verify FPVB algorithm. For free-phase migration, the Kinematic Oily Pollutant Transport (KOPT) model was used to determine LNAPL movement velocity and leakage time. The correlations of water saturation, residual LNAPL saturation and the cumulative dissolution ratio of residual LNAPL were described using an empirical formula for the precipitation leaching process. Equations for diesel volatilization kinetics and first order degradation were used to describe the natural attenuation processes. Coupling the algorithms for the different stages gave the final FPVB algorithm. The FPVB algorithm was used to describe the pollution situation at a real site, and the results were consistent with the actual situation. The FPVB algorithm could be used to quickly assess the scale and degree of pollution with little information on the parameters for the actual LNAPL leakage event.

The influence of organic solvents on phenylethylamines in capillary zone electrophoresis

The aim of this study was to investigate the influence of organic solvents on the electrophoretic separation of phenylethylamines. The background electrolyte composition was adjusted with different protic (methanol, ethanol, and 2-propanol) and aprotic (dimethyl sulfoxide and acetonitrile) solvents. Two groups of analytes were studied. The first group contained phenylethylamines with an amine group only, DL-1-phenylethylamine and amphetamine. The second group represented phenylethylamines with both amine and phenolic hydroxyl groups, dopamine and tyramine. Experiments revealed no or minor influence of the organic modifiers on the electromigration behavior of the analytes from the first group (containing only the amine group) and a drastic effect on the second group (containing the additional phenolic hydroxyl group). Dopamine and tyramine showed various electrostatic, hydrophobic, and hydrogen-bonding interactions with both protic and aprotic organic solvents. The dependence of the electrophoretic mobility of dopamine and tyramine on the concentration of the organic solvents provided direct evidence of the formation of hydrogen bonds between dopamine or tyramine and the organic solvent. The baseline separation was achieved by the addition of at least 20% v/v of organic solvent (protic or aprotic) to the background electrolyte. The analyte migration time repeatabilities were within 0.7–4.1% for absolute and 0.2–1.9% for normalised migration times. The proposed bonding mechanism and behavior of phenylethylamines were examined and confirmed by NMR spectroscopy.

Міграційна мобільність населення в економічних дослідженнях: тео-ретичні аспекти

Migration issues need more extensive coverage in fundamental studies. One of the important tasks is to specify the conceptual and terminological apparatus of migration research and eliminate discussions in the migration thesaurus, in particular on the content of migration as a mobility form. In view of this, the purpose of the article is to substantiate the content of migration mobility of the population as a fundamental economic category that forms the theoretical foundations of migration research with the separation of a new migration science. The scientific novelty is the substantiation of the basic provisions of migration studies and the specification of its migration thesaurus in terms of determining the content of migration mobility. The methodological basis of the study is a dialectical approach, abstract-logical method, method of systematization and generalization, the use of which allowed to formulate the basic provisions of migration and clarify its conceptual and terminological apparatus. The formation of migration studies is confirmed by the conclusions of leading economists and demographers. Migration studies accumulates knowledge, approaches to analysis and practical recommendations for migration regulation. Given the complexity of the migration essence, migration studies is formed as a science-interdisciplinary synthesis at the junction of socioeconomics, demography, spatial science and regional studies. The issues of migration studies develop the following directions: fundamental migration studies, which determines the basic provisions for understanding mig ration in the indicator-factor complex, based on migration theories, concepts, principles, mig ration terminology; analytical migration studies, which reveals the methodology of analyzing migration in terms of causes, conditions, trends; migration qualiology, which emphasizes the methodology of quantitative and qualitative assessment of the migration impact on various phenomena and processes. The main branches of migration studies are economic, demographic, social and political, the results of which comprehensively reveal the possibilities of solving the migration problem by ensuring a positive consequence for person, society and state. The development of migration research requires deepening and modernization of the methodology of migration analysis with the correct use of terminology. In the migration thesaurus there are a number of similar concepts, each of which has specifics. Based on terminological contra dictions, the main approaches to understanding migration as phenomenon, process, system, sign and form of mobility are generalized. The multifaceted concept of migration mobility of the population raises the scientific and practical value of its research. In this regard, the content of migration mobility is revealed, its spatio-temporal, causal and consequential characteristics in the context of the impact on human development are specified, and the prospects for improving methodological approaches to analyzing youth mobility are indicated.

Enantioseparation in capillary eletrochromatography by covalent organic framework coating prepared in situ

Chiral covalent organic frameworks (CCOFs) have recently exhibited particularly promising potential as effective chiral stationary phases (CSPs) for open tubular capillary electrochromatography (OT-CEC) enantioseparation. However, it remains difficult to synthesis of CCOFs and preparation of CCOFs coated capillary under mild reaction conditions. In this work, we designed and fabricated a CCOF (CB-DA-COF) with high chemical stability and high specific surface area at room temperature. Then, through one-step in situ growth method, the chiral CB-DA-COF coated capillary was fabricated at room temperature for the first time. This method requires neither pre-modification to the capillary by organic molecular building units nor harsh reaction conditions, and the preparation time of the CCOF coating was significantly shortened (within 2 h). This chiral CB-DA-COF coated capillary showed excellent enantioseparation ability and stability. Under optimal conditions, rapid enantioseparation (within 5 min) could be achieved for six enantiomers including terbutaline, propranolol, phenylephrine, verapamil, norepinephrine and isoprenaline. And, no significant change was observed in enantioseparation efficiency after over 200 runs. The relative standard deviations (RSDs) of the analyte's migration time for intra-day, inter-day and column-to-column were within the range of 0.8-3.5% (n = 5), 1.5-4.7% (n = 3) and 4.3-8.3% (n = 3), respectively. In addition, the enantioseparation mechanism was studied, which indicated that binding energy between of enantiomers and chiral site were the main factors for enantioseparation.

Characterization of Polyester Coatings Intended for Food Contact by Different Analytical Techniques and Migration Testing by LC-MSn.

Polymeric coating formulations may contain different components such as cross-linking agents, resins, lubricants, and solvents, among others. If the reaction process or curing conditions are not applied in a proper way, these components may remain unreacted in the polymeric network and could be released and migrate into foods. In this study, several polyester coatings intended for food contact were investigated. Firstly, Fourier-transform infrared spectroscopy with an attenuated total reflectance (ATR-FTIR) spectrometer and confocal Raman microscopy were used to identify the type of coating. Then, different techniques, including gas chromatography coupled to mass spectrometry (GC-MS) and analysis by matrix-assisted laser desorption coupled to time-of-flight mass spectrometry (MALDI-TOF-MS), among others, were used to investigate the potential volatile and non-volatile migrants. Moreover, migration assays were carried out to evaluate the presence of monomers and to tentatively identify possible oligomers below 1000 Da. The analyses were performed by liquid chromatography coupled to ion trap mass spectrometry (LC-MSn). Using the information collected from each analytical technique, it was possible to elucidate some of the starting substances used in the formulation of the polyester coatings analyzed in this study. In migration tests, several polyester oligomers were tentatively identified for which there is not toxicological data available and, therefore, no migration limits established to date.

Ultrasound-assisted electromembrane extraction with supported semi-liquid membrane

Electromembrane extraction (EME), involving the migration of charged analytes across a supported liquid membrane (SLM) with an external power supply, is a promising sample preparation method in analytical chemistry. However, the presence of boundary double layers at the SLM/solution interfaces often restricts extraction efficiency. To avoid this, the current work proposed an ultrasound-assisted EME (UA-EME) method based on a novel type of supported semi-liquid membrane (SsLM). The characterizations showed that the SsLM was stable under ultrasound conditions. Ultrasound was found to reduce the boundary double layers and thus increase the mass transfer. Major operational parameters in UA-EME including ultrasound power density, temperature, applied voltage and extraction time were optimized with haloperidol, fluoxetine, and sertraline as model analytes. Under the optimal conditions, extraction recoveries of model analytes in water samples were in the range of 66.8%–91.6%. When this UA-EME method was coupled with LC-MS/MS for detection of the target analytes in human urine samples, the linear range of the analytical method was 10–1000 ng mL−1, with R2 > 0.997 for all analytes. The limits of detection (LOD) and limits of quantification (LOQ) were in the range of 1.7–2.1 ng mL−1 and 5.7–6.7 ng mL−1, respectively. The UA-EME expands the application field of ultrasound chemistry and will be very important in development of stable and fast sample preparation systems in the future.

Population Spatial Mobility: Monitoring, Methodology of Formation, Features of Regulation

Spatial mobility is a topical concept of analytical migration science, which makes it possible to assess the desires, readiness and capabilities of the population to move over certain distances and time. In the management of spatial mobility assessment requires the organization of systematic monitoring, which includes identifying the mobility potential in spatial and temporal interpretation, the status of its implementation in migration and tourism directions, the causes of displacement with an assessment of the deprivation level, as well as the consequences of displacement, in particular in the context of achieving human development goals and capitalizing on human potential. The quality system of monitoring of population spatial mobility should be the basis for mobility regulation. The formation of such systems should be carried out in several stages: development of unified approach to the formation of accounting and mobility statistics; development of methodology and conducting selective sociological survey on the population spatial mobility with the participation of state statistics authorities and the International Organization for Migration (internal and external mobility); development of a indicators system for the monitoring of population spatial mobility in context of achieving human development goals. One of the main results of the monitoring of population spatial mobility is to find out the main groups of the potentially active population in the coordinates of space and time: internal mobility, including intra-settlement, intra-regional, inter-regional (the main purpose of regulation is the development of transport infrastructure); middle-distance mobility, including cross-border, intra-state (the main purpose of regulation is the effective use of migration capital and tourism costs); long-distance mobility, including continental, remote (the main purpose of regulation is to ensure circulating migration; keeping in touch through the Diaspora Institute). Formation of high-quality system of information support for migration regulation through the monitoring of population spatial mobility will allow to depart from the practice of biased accounting of migration processes with limited and non-systematic presentation of statistics.

Migration activity of the population between Ukraine and Hungary in the context of geopolitical confrontations

The comprehensive analysis of migration activity of the population between Ukraine and Hungary, which is the basis for substantiating the priorities of its regulation in the defined territorial migration system, is carried out in the article. The study subject is theoretical and applied principles of analysis of migration activity of the population within a specific territorial migration system. The research methodology is formed by the fundamental provisions of analytical migration science with the definition of migration activity, which reflects the potential and real ability of the population to move. The article results are the deepening of the theoretical bases of the study of migration activity of the population, the method of complex migration analysis between Ukraine and Hungary with using the national and international statistical base. Complex analysis covers an identification of the features of infrastructure providing and legal environment of migration (visa regime, the operation of the agreement on the rules of local border traffic), tendencies of crossing the state border (Ukrainian and Hungarian statistics), including in the context of border crossing points, determination of educational and labor migration features, naturalization practices and residence of Ukrainian citizens on the Hungary territory. Particular attention is paid to the asymmetric questions of migration activity of the population between Ukraine and Hungary. Complex analysis is complemented by comparisons of demographic, social and economic indicators of countries. The specificity of migration activity of the population in the UkrainianHungarian migration system on the basis of the conducted analysis is generalized – the primacy of ethnocultural determinants of displacement with influences localization on the residents of Transcarpathian region; rapid growth dynamics of the migrants number from Ukraine to Hungary. The main problems of migration activity of the population between Ukraine and Hungary are updated: political and legal character – dual citizenship of a part of the population of the Transcarpathian border regions, which can serve as an occasion for geopolitical speculation; informational character – the rapid growth in the number of Ukrainian citizens, who go to Hungary for long-term residence; socio-cultural character – influence of the «Greater Hungary» ideas on a part of the Transcarpathia population, especially the border regions, which identifies itself with the Hungarians, or as a last resort with the Ruthenians and does not speak Ukrainian.

Electromembrane extraction of phenytoin from biological fluids: A survey on the effects of molecularly imprinted polymer and carbon nanotubes on extraction efficiency

In the present study, an electrically-assisted microextraction method termed electromembrane extraction (EME) followed by a simple high performance liquid chromatography-ultraviolet detection was developed and validated for the determination of phenytoin in human biological samples. Main parameters influencing the electromembrane extraction were evaluated and optimized using the Box-Behnken experimental design. The membrane consisted of 1-octanol immobilized in the pores of a hollow fiber. As a driving force, a 40 V electric field was applied to facilitate the migration of analytes from the sample solution to an acceptor solution through a supported liquid membrane. The optimum donor and acceptor solutions pHs were achieved 10 and 13, respectively. The enrichment factor was > 82 within 15 min led to 55% absolute extraction recovery. In optimum conditions, the method provided the linearity in the range of 10–1000 ng/mL (R2 >0.999). The repeatability of the method was indicated as relative standard deviations (%RSD) between 3.6% and 8.9% (n = 3). The limits of detection and quantitation were 3.0 and 10.0 ng/mL, respectively. The sensitivity of HPLC-UV for determining phenytoin was enhanced by electromembrane extraction. Also, in this study, the effects of some nano-sorbents like carbon nanotubes and molecularly imprinted polymer on membrane performance and EME efficiency were evaluated. The EME technique can be introduced as a new approach for screening of molecularly imprinted polymers in their primary steps of characterization. Finally, the proposed EME-HPLC-UV method was applied for phenytoin determination in human plasma and urine samples with relative recoveries ranged between 88–92% indicating the reliability of the method.