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Background: Sample preparation has gained significant recognition in the chemical analysis workflow. Substantial efforts have been made to simplify the comprehensive process of sample preparation that is focused on green sample preparation methodology, including the miniaturization of extraction method, elimination of the sample pre-treatment as well as the post-treatment steps, elimination of toxic as well as hazardous organic solvent consumption, reduction in sample volume requirements, reducing the extraction time, maximization of the extraction efficiency and possible automation. Methods: Among various microextraction processes, liquid-phase microextraction (LPME) is most abundantly used in the extraction of the target analytes. The salting-out phenomenon has been introduced into the LPME procedure and has been raised as a new technique called the ‘Salt-Assisted Liquid-Liquid Microextraction (SALLME)’. The principle is based on decreasing the solubility of less polar solvent or analyte with an increase in the concentration of the salt in aqueous solution leading to two-phase separation. Conclusion: SALLME is mainly based on the salting-out phase separation phenomenon. It is important to optimize the SALLME experimental parameters, such as solvent volume, salt amount, and extraction time, to achieve the maximum extraction capacity of the target analytes from the sample matrices. Conclusion: SALLME proved to be a simple, rapid, and cost-effective sample preparation technique for the efficient extraction and preconcentration of organic and inorganic contaminants from various sample matrices, including environmental, biological, and food samples. SALLME exhibits higher extraction efficiency and recovery and is compatible with multiple analytical instruments. This review provides an overview of developments in SALLME technique and its applications to date.

Numerical simulations of silicone oil–water two-phase turbulent dispersion mixing in Q-type static mixers (QSM) are performed using computational fluid dynamics (CFD) coupled with a population bala...

We investigated the kinematic viscosity and electrical resistivity of the multicomponent Fe74Cu1Nb1.5Mo1.5B8.5Si13.5 melt during three heating–cooling cycles. The temperature dependence of kinematic viscosity and electrical resistivity have the anomalous zones in the same temperature range and they are associated with the liquid–liquid structure transition (LLST). The anomalies were explained by changes in the activation energy and the cluster size. As the cluster size decreases, the activation energy decreases, but the viscosity and electrical resistance increase. LLST begins with the cluster dissolution, and as a result, the Arrhenius plot becomes nonlinear in the transition temperature range. After three cycles of heating–cooling, the temperature dependences of the kinematic viscosity and electrical resistance did not qualitatively change, and this allows us to conclude that LLST is thermoreversible. With an increase in the number of thermal cycles, the activation energy of viscous flow decreases, as well as the onset temperature and temperature range of LLST.

A hydrophobic deep eutectic solvent (DES) based vortex-assisted liquid-liquid microextraction (LLME) procedure was developed for the effective and rapid determination of thiophanate-methyl (TM) and carbendazim (CA) in lake water and tap water samples, with an excellence extraction efficiency (recovery: 87.2% to 97.4%, enrichment factor: 87.2 to 97.4). Twelve hydrophobic DESs based on terpenoids and fatty acids/alcohols were prepared, and those with the highest recovery for TM and CA were selected. The main parameters, including assisting methods, molar ratio of DES components, volume of DES, and NaCl content that may affect vortex-assisted LLME, were optimized. The intra-day and inter-day relative standard deviation (RSD) of this method were from 1.7% to 3.8% and 1.8% to 4.1%, showing excellent precision. The proposed method exhibited suitable limits of detection (TM: 0.053 µg/mL; CA: 0.007 µg/mL) and limits of quantification (TM: 0.177 µg/mL; CA: 0.024 µg/mL).

The presence or absence of liquid–liquid phase separation (LLPS) in aerosol particles containing oxidized organic species and inorganic salts affects particle morphology and influences uptake into, diffusion through, and reactivity within those particles. We report here an accessible method, similar to ice core analyses, using solutions that are relevant for both aerosol chemical systems and aqueous two-phase extraction systems and contain ammonium sulfate and one of eight alcohols (methanol, ethanol, 1-propanol, 2-propanol, 2-butaonol, 3-methyl-2-butanol, 1,2-propanediol, or 1,3-propanediol) frozen in articulated (bendable) straws to probe LLPS. For alcohols with negative octanol–water partitioning coefficient (KOW) values and O/C ratios ≥0.5, no LLPS occurs, while for alcohols with positive KOW values and O/C ratios ≤0.33, phase separation always occurs, both findings consistent with observations using different experimental techniques. When a third species, glyoxal, is added, the glyoxal stays in the aqueous phase, regardless of whether LLPS occurs. When phase separation occurs, the glyoxal forms a strong intermolecular interaction with the sulfate ion, red-shifting the ν3(SO42–) peak by 15 cm–1. These results provide evidence of chemical interactions within phase-separated systems that have implications for understanding chemical reactivity within those, and related, systems.

Here, the liquid–liquid phase separation (LLPS) in aqueous solutions containing poly(ethylene glycol) (PEG) methacrylate homopolymers is reported for the first time. In this study, the thermoresponse of concentrated solutions of DEGMA60 (two ethylene glycol, EG, groups) TEGMA71 (three EG groups), OEGMA300x (4.5 in average EG groups) of varying molar masses (MM), and OEGMA50028 (nine in average EG groups) is discussed. Interestingly, the temperature of LLPS (TLLPS) is controlled by the length of the PEG side chain, the MM of the OEGMA300x and the polymer concentration. More specifically, the transition temperature decreases with: (i) Decrease in the length of the PEG side chain, (ii) increase in MM of the OEGMA300x, and increase in concentration. In addition, LLPS is also observed in mixtures of OEGMA300x with Pluronic® F127. In conclusion, these systems present a thermally induced LLPS, with the transition temperature being finely tuned to room temperature when DEGMA is used. These systems find potential use in numerous applications, varying from purification to “water-in-water” emulsions.

Abstract A method is proposed for the determination of some ketosteroids in human urine, including enzymatic hydrolysis using β-glucuronidase from E. coli followed by dispersive liquid-liquid microextraction, derivatization of analytes with hydroxylamine, and detection by reversed-phase ultra-HPLC–quadrupole time-of-flight mass spectrometry. Optimization of extraction and derivatization conditions of the studied compounds made it possible to find that the highest recoveries were achieved using an acetone–chloroform mixture as a dispersant and an extractant, and the completeness of the derivatization reaction was achieved by thermostating the sample at 70°C for 90 min. The proposed method has high sensitivity (limits of detection in the range of 0.1–0.25 ng/mL) and a wide linearity range.

While many studies have investigated synergic interactions between surfactants in mixed systems, understanding possible competitive behaviors between interfacial components of binary surfactant systems is necessary for the optimized efficacy of applications dependent on surface properties. Such is the focus of these studies in which the surface behavior of a binary surfactant mixture containing nonionic (Span-80) and anionic (AOT) components adsorbing to the oil/water interface was investigated with vibrational sum-frequency (VSF) spectroscopy and surface tensiometry experimental methods. Time-dependent spectroscopic studies reveal that while both nonionic and anionic surfactants initially adsorb to the interface, anionic surfactants desorb over time as the nonionic surfactant continues to adsorb. Concentration studies that vary the ratio of Span-80 to AOT in bulk solution show that the nonionic surfactant preferentially adsorbs to the oil/water interface over the anionic surfactant. These studies have important implications for applications in which mixed surfactant systems are used to alter interfacial properties, such as pharmaceuticals, industrial films, and environmental remediation.

Liquid–liquid phase separation (LLPS) during crystallization development of pharmaceuticals is being reported increasingly in recent years. It often causes quality issues such as failure of impurity reject and fragile morphology. In worst cases, crystallization cannot proceed at all after LLPS occurs. Many studies have been published on LLPS during crystallization and an analysis and synthesis of the current state-of-art is needed. In this review, recent advances in LLPS research will be summarized, including brief theoretical interpretations of LLPS, characteristics in phase diagrams and measurement methods for representative model systems, strategies to suppress LLPS, crystallization development in the presence of LLPS and options when direct crystallization fails due to LLPS. This review aims to provide a framework to deal with the occurrence of LLPS during crystallization development.

Liquid–liquid phase separation (LLPS) is critical for assembling membraneless organelles (MLOs) such as nucleoli, P-bodies, and stress granules, which are involved in various physiological processes and pathological conditions. While the critical role of RNA in the formation and the maintenance of MLOs is increasingly appreciated, there is still a lack of specific resources for LLPS-related RNAs. Here, we presented RPS (http://rps.renlab.org), a comprehensive database of LLPS-related RNAs in 20 distinct biomolecular condensates from eukaryotes and viruses. Currently, RPS contains 21,613 LLPS-related RNAs with three different evidence types, including ‘Reviewed’, ‘High-throughput’ and ‘Predicted’. RPS provides extensive annotations of LLPS-associated RNA properties, including sequence features, RNA structures, RNA–protein/RNA–RNA interactions, and RNA modifications. Moreover, RPS also provides comprehensive disease annotations to help users to explore the relationship between LLPS and disease. The user-friendly web interface of RPS allows users to access the data efficiently. In summary, we believe that RPS will serve as a valuable platform to study the role of RNA in LLPS and further improve our understanding of the biological functions of LLPS.

Exploiting new interface-active solid catalysts is crucial to construct efficient Pickering emulsion systems for biphasic catalysis. In this work, ultrathin g-C3N4 nanosheets (g-C3N4-NSs) were developed as a new solid emulsifier to directly position catalytic sites at oil-water interfaces for improving the reaction efficiency of a biphasic reaction. Exemplified by a metal-involved biphasic reaction of nitroarenes reduction, the developed Pd/g-C3N4-NSs catalyst with Pd nanoparticles loaded on the surface of g-C3N4-NSs exhibited excellent activity with a catalytic efficiency of 1220 h-1. Such activity was 4.2 and 17.9 times higher than those of Pd/g-C3N4-bulk and the ordinary Pd/C8-SiO2 catalyst, respectively. Also, in the biphasic oxidation reaction of alcohols, Pd/g-C3N4-NSs achieved a 2.3-fold activity enhancement. It was found by analyzing the solidified emulsion droplets that the Pd/g-C3N4-NSs catalyst was parallelly assembled at the oil-water interfaces. Because of the ultrathin thickness of g-C3N4-NSs, such a unique interfacial assembly behavior allowed precise positioning of Pd nanoparticles at the oil-water interfaces. As a result, the oil-soluble reactant could directly react with the water-soluble reactant at the oil-water interface hosting the Pd nanoparticles. Our elaborately designed reaction interface was believed to substantially avoid the diffusion barrier between oil-soluble and water-soluble reactants and then to significantly enhance the reactivity of biphasic reactions. This work highlights the importance of the interfacial location of catalytic sites in biphasic catalysis.

Dispersive liquid-liquid microextraction is one of the most widely used microextraction techniques currently in the Analytical Chemistry field, mainly due to its simplicity and rapidity. The operational mode of this approach has been constantly changing since its introduction, adapting to new trends and applications. Most of these changes are related to the nature of the solvent employed for the microextraction. From the classical halogenated solvents (e.g., chloroform or dichloromethane), different alternatives have been proposed in order to obtain safer and non-pollutants microextraction applications. In this sense, low density solvents, such as alkanols, switchable hydrophobicity solvents and ionic liquids were the first and most popular replacements for halogenated solvents, which provided similar or better results than these classical dispersive liquid-liquid microextraction solvents. However, despite the good performances obtained with low density solvents and ionic liquids, researchers have continued investigating in order to obtain even greener solvents for dispersive liquid-liquid microextraction. For that reason, in this review, the evolution over the last five years of the three types of solvents already mentioned and two of the most promising solvent alternatives (i.e., deep eutectic solvents and supramolecular solvents), have been studied in detail with the purpose of discussing which one provides the greenest alternative. This article is protected by copyright. All rights reserved.

In syringe-supramolecular dispersive liquid-liquid microextraction followed by flame atomic absorption spectrometry has been designed for extraction and speciation of iron in different samples. Fe(...

In this study, a new microextraction method based on hydrophobic deep eutectic solvents was developed for the extraction and preconcentration of organophosphorus pesticides from beverage samples. The hydrophobic deep eutectic solvents were synthesized from choline chloride and 4-chlorophenol. Main experimental parameters of the microextraction method were investigated to improve the extraction efficiency. The proposed method achieved a satisfactory linear range between 50 and 2,000 μg L−1 with coefficient of determination greater than 0.9939. The extraction recoveries and enrichment factor of five organophosphorus pesticides at three added levels ranged from 71.68 to 113.18% and 71.43–111.11 were obtained with the acceptable relative standard deviation ranged from 1.37 to 11.92%. Limits of detection and quantification were found to be 0.05–0.3 μg L−1 and 0.17–1 μg L−1, respectively. Finally, the methods were successfully applied for the determination of five organophosphorus pesticide in orange juice and green tea.

The effects of mass transfer were quantified for the effective performance of mixtures between partially miscible phases, or for the promotion of their separations. To consolidate the analysis of heterogeneous liquid–liquid processes, variations in the composition of the liquid phases over the evolution of contact operations were considered, detailing the physical mechanisms involved in the mixtures of oil (soy, sunflower) and alcohol (methanol, ethanol), and in the separation between biodiesel and glycerin. Based on experimental evaluations, the average distribution coefficients for triglycerides (oil-alcohol) and glycerol (biodiesel-glycerin) were estimated at 1.31 and 1.46, and 3.42 × 10−2 and 4.06 × 10–2, for soybean and sunflower, respectively, while their mass transfer coefficients, depending on their concentration ranges in the phase, varied in orders of magnitude from 10−2 s−1 to 10–4 s−1. Including the values of the physical parameters, a heterogeneous model for the alkaline transesterification of soybean oil (methanol, ethanol, NaOH, 25°C, 40°C, 60°C, 600 rpm) was validated.

The occurrence of unidirectional ejection phenomena (both continuous & intermittent), during mass transfer in binary and ternary systems respectively; reported earlier, have been explained on the b...

Los cereales y sus subproductos son la base de la alimentación en México y en países en desarrollo. El cereal seco es un alimento basado en granos de cereales y/o leguminosas que se elaboran para lograr un escaso contenido de humedad y se fragmentan para permitir su dilución con agua, leche y otro líquido conveniente para niños y lactantes. Los efectos adversos de las micotoxinas incluyen problemas en el crecimiento infantil, defectos en el desarrollo del tubo neural, daños al sistema inmunológico, enfermedades renales, y mayores probabilidades de desarrollar cáncer de hígado y esófago. Por lo cual, su estudio es de gran importancia en lo que respecta a la salud pública. Las aflatoxinas son carcinógenos potentes que pueden afectar especialmente al hígado y al riñón; son causa de cáncer hepático y se han relacionado con otros tipos de cáncer. El presente trabajo consistió en determinar la cantidad de aflatoxinas (AF) totales en alimentos de consumo infantil, extrayéndose de éstos mediante columnas de anticuerpos monoclonales para conocer sus niveles de concentración con el método "Aflatest - Vicam". Las muestras analizadas fueron principalmente cereales para consumo infantil entre otros productos como avenas, galletas y frituras. Los resultados reportaron que el 83.3% de los productos analizados se encontraban libres de aflatoxinas, mientras que el 16.7% arrojaron concentraciones mínimas que no rebasaron los límites máximos permisibles por la NOM-187-SSAI/SCFI-2002, la cual establece 20 µg/kg de concentración máxima en harinas y cereales. Cereals and their by-products are the basis of food in Mexico and developing countries. Dry cereal is a food based on grains of cereals and/or leguminous plants which are made to achieve a low moisture content and are fragmented to allow dilution with water, milk and other liquid liquid suitable for infants and infants. Adverse effects of mycotoxins include problems in childhood growth, defects in the development of the neuronal tube, damage to the immune system kidney diseases, and more likely to develop liver cancer and esophageal cancer. Therefore, his study is of great importance in regards to public health. Aflatoxins are potent carcinogens that can affect any organ or system, and especially to the liver and kidney; they cause liver cancer and have been linked to other types of cancer. The present work consisted of determining the amount of total aflatoxins (AF) in infant foods by monoclonal antibodies to know their concentration levels by the "aflatest - vicam" method, the samples analysed were mainly cereals for infant consumption among other products such as oats, biscuits and fritters. The results reported that 83.3% of the products analysed were free of aflatoxins, while 16.7% reported minimal concentrations, thus not exceeding the maximum permissible concentrations of the NOM-187-SSAI/SCFI-2002 which sets 20 µg/kg maximum concentration in flour and cereals.

Dispersive liquid-liquid microextraction (DLLME) is a useful preconcentration technique but its direct application is limited to aqueous samples. Two pretreatment methods for solid samples, QuEChERS (quick easy cheap efficient rugged and safe) and a standard method, were used to isolate four polycyclic aromatic hydrocarbons (PAHs) from the sample matrix. However, since these methods result in analyte dilution, DLLME was used to augment them by concentrating the analytes from 8.0 mL of sample into 150 ��L of 1,2-dichloroethane. Under the optimum conditions, the instrumental detection limit was enhanced by approximately 100-fold for chrysene, benzo[a]pyrene, benz[a]anthracene, and benzo[k]fluoranthene with corresponding detection limits of 29, 29, 30, and 28 ng/L, respectively. The precision of the method based on inter-analyst and inter-day analysis yielded relative standard deviations less than 9.0 and 4.0%, respectively. The optimized method was applied to snail samples spiked at 5.0, 10, 20, and 50 ng/g and the recoveries were nearly 100%. Matrix matched standards were also used to determine the recoveries; the results did not vary significantly from the direct calibration recoveries.

The aim of this study is the extraction and determination of di(2-ethylhexyl) adipate and three phthalate esters including di-iso-butyl phthalate, di-n-butyl-phthalate, and di-(2-ethylhexyl) phthal...

Made available in DSpace on 2022-04-28T19:42:13Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-08-12 This paper reports experimental results and thermodynamic modeling of the liquid-liquid equilibrium (LLE) of the system chicha biodiesel (Sterculia striata) + glycerol + ethanol. Binodal curves and tie lines were obtained at different temperatures (303.15, 318.15, and 333.15 K) and atmospheric pressure (101.3 kPa). The quality of the experimental data was evaluated using the criteria of Marcilla and co-workers. The nonrandom two-liquid (NRTL) and analytical solutions of groups (ASOG) models were used to correlate the LLE data. Both models well fitted the experimental data with root-mean-square deviations (rmsd) not greater than 1.5%. Laboratory of Separation Systems and Process Optimization (LASSOP) Center of Technology Federal University of Alagoas, Alagoas Department of Chemical Engineering Federal University of Parana, Paraná Engineering School of Lorena Department of Chemical Engineering University of Sao Paulo (USP), São Paulo Department of Energy Engineering Sao Paulo State University (UNESP), São Paulo Department of Energy Engineering Sao Paulo State University (UNESP), São Paulo

Biomolecular condensates comprised of specific proteins and nucleic acids are now recognized as one of the key organizing mechanisms in eukaryotic cells. However, the specific roles played by the nucleic acid secondary structure and sequence in biomolecular phase separation are still not clear. Here, utilizing giant membrane vesicles (GMVs) as a protocell model, we found that single-stranded DNA (ssDNA) with a parallel G-quadruplex structure could functionally cooperate with a G-quadruplex-binding protein to form speckle-like puncta inside the GMVs. The clustering behavior is dependent on the structural diversity of G-quadruplexes, and the reversible clustering behavior implicated a new pathway in dynamically regulating the formation of biomolecular condensates. This finding represents a potential link between G-quadruplex-binding proteins and the resulting G-quadruplex-mediated biomolecular phase separation, which would gain insight into a wide range of biological processes associated with nucleic acid-modulated phase separation inside living cells.

Aim: A pH-induced homogeneous liquid–liquid microextraction (HLLME) using a new switchable deep eutectic solvent has been used for the extraction of three antiepileptic drugs from breast milk samples. Methodology: This method is based on phase separation by changing pH. An ammonia solution and a phosphocholine chloride: hexanoic acid: p-aminophenol deep eutectic solvents were used as the phase separation agent and extraction solvent, respectively. Results: Significant factors were studied and the detection limits and enrichment factors were in the ranges of 0.009–0.19 ng ml-1 and 182–212 for the analytes, respectively. Also, linear ranges were wide (0.63–500 ng ml-1) and the method precision was acceptable. Conclusion: The introduced method was successfully applied for the determination of the analyte concentrations in breast milk samples.

The jamming of nanoparticle surfactants (NPSs) at liquid-liquid interface imparts attractive properties to the interfacial assemblies and enables the structuring of liquids. Herein, we report photoresponsive supramolecular microcapsules with jammed NPS assemblies at the oil-water interface, taking advantage of host-guest molecular recognition. The permeability of the colloidal membrane can be effectively manipulated by switching the NPSs from a jammed state to an unjammed state with a photo trigger, leading to a controlled molecular diffusion and release, affording a versatile platform for the construction of next generation smart microcapsule systems.

In the present study, a simple, rapid and efficient dispersive liquid–liquid microextraction (DLLME) coupled with spectrofluorimetry and chemometrics methods have been proposed for the preconcentration and determination of fenthion in water samples. Box–Behnken design was applied for multivariate optimization of the extraction conditions (sample pH, the volume of dispersive solvent and volume of extraction solvent). Analysis of variance was performed to study the statistical significance of the variables, their interactions and the model. Under the optimum conditions, the calibration graph was linear in the range of 5.0–110.0 ng mL-1 with the detection limit of 1.23 ng mL-1 (3Sb/m). Parallel factor analysis (PARAFAC) and partial least square (PLS) modelling were applied for the multivariate calibration of the spectrofluorimetric data. The orthogonal signal correction (OSC) was applied for preprocessing of data matrices and the prediction results of model, and the analysis results were statistically compared. The accuracy of the methods, evaluated by the root mean square error of prediction (RMSEP) for fenthion by OSC-PARAFAC and OSC-PLS models were 0.37 and 0.78, respectively. The proposed procedure could be successfully applied for the determination of fenthion in water samples.