Microemulsion Composition Research Articles

Analysis of Aceclofenac, Ketorolac, and Sulindac in Human Urine Using the Microemulsion Electrokinetic Chromatography Method

A method to determine aceclofenac, ketorolac, and sulindac in human urine samples using microemulsion electrokinetic chromatography (MEEKC) has been developed in this study. The optimization of MEEKC conditions was carried out by changing the microemulsion compositions including the buffer pH, borate salt concentration, surfactant concentration, co-surfactant concentration, organic modifier concentration, and oil droplet concentration. The optimum separation of selected drugs was obtained with a composition of microemulsion containing 10 mM borate buffer pH 9, 0.5% sodium dodecyl sulphate (SDS), 6.6% n-butanol, 6.0% acetonitrile, and 0.8% ethyl acetate. Excellent linearity was obtained in the range concentration of 25 to 200 ppm with r2 > 0.999. Limits of detection (LOD, S/N = 3) and limits of quantification (LOQ, S/N = 10) were 2.72 to 4.75 and 9.08 to 15.85 ppm, respectively. The solid-phase extraction (SPE) method using C-18 as an adsorbent and the solid phase micro-tip extraction (SPMTE) method using multiwalled carbon nanotubes (MWCNTs) as an adsorbent were used to clean-up and pre-concentrate the urine samples prior to the MEEKC analysis. The best recoveries of the selected drugs in the spiked urine sample were 91 to 103% with RSD of 1.26 to 4.03% (n = 3) using the SPE-MEEKC method.

Investigation of Structural, Photoelectrochemical, Magnetic and Catalytic Properties of LaSrNiO4, LaSrCuO4, LaSrCoO4 Nanoparticles Synthesised by Reverse Micellar Route

AbstractLaSrCoO4, LaSrNiO4 and LaSrCuO4 were synthesised by the reverse micellar route by using three different microemulsion compositions. The as prepared nanostructures were characterised by powder X‐ray diffraction (PXRD), field emission scanning electron microscopy, energy dispersive X‐ray spectroscopy and transmission electron microscopy. The PXRD of all samples indicate pure phases which crystallize into a tetragonal system. The particle size and shape of nanoparticles varies with microemulsion system. Magnetisation studies suggested that two of the LaSrCoO4 samples display canted antiferromagnetism while the others showed no sign of long‐range ordering. The LaSrNiO4 and LaSrCuO4 samples seemed to show spin glass behaviour. Some of these materials were successfully used as catalysts for organic transformations. The esterification of aldehydes in the presence of alkyl halides and alcohols has been made mild and practicable with a copper catalysed TBHP/DTBP promoting reaction. This approach is suitable to a wide variety of aldehydes, including those that are notoriously difficult to convert through the C(sp2)−H bond scission to produce the required esters in good to outstanding yield.

Bimetallic nanoparticles via microemulsions: The effects of concentration in surface composition

The precise control of surface composition is crucial for enhancing the efficiency of bimetallic nanocatalysts. The scarcity and contradictory nature of experimental results keep open the question of whether reactant concentration promotes the enrichment of the nanoparticle surface with the slower reduction metal. A computer simulation study is carried out to thoroughly investigate how the initial concentration of metals salts modifies the resulting surface for various metal pairs and under different microemulsion compositions. Across all cases, it was observed that less Au is located at the surface as concentration increases. The resulting surface compositions are explained based on the relative rates of the two metals, which consider not only the reduction rate of particular metal pair but also factors such as the concentration of reactants, the intermicellar exchange rate, and the contribution of ripening to growth. This study provides a comprehensive understanding of the mechanism of nanoparticle formation in microemulsions and enables the proposal of practical guidelines for obtaining bimetallic nanoparticles with customized surfaces.

Microemulsion-Based Polymer Gels with Ketoprofen and Menthol: Physicochemical Properties and Drug Release Studies.

Ketoprofen is a non-steroidal, anti-inflammatory drug frequently incorporated in topical dosage forms which are an interesting alternatives for oral formulations. However, due to the physiological barrier function of skin, topical formulations may require some approaches to improve drug permeation across the skin. In this study, ketoprofen-loaded microemulsion-based gels with the addition of menthol, commonly known for absorption-enhancing activity in dermal products, were investigated. The main objective of this study was to analyze the physicochemical properties of the obtained gels in terms of topical application and to investigate the correlation between the gel composition and its mechanical properties and the drug release process. Microemulsion composition was selected with the use of a pseudoternary plot and the selected systems were tested for electrical conductivity, viscosity, pH, and particle diameter. The polymer gels obtained with Carbopol® EZ-3 were subjected to rheological and textural studies, as well as the drug release experiment. The obtained results indicate that the presence of ketoprofen slightly decreased yield stress values. A stronger effect was exerted by menthol presence, even though it was independent of menthol concentration. A similar tendency was seen for hardness and adhesiveness, as tested in texture profile analysis. Sample cohesiveness and the drug release rate were independent of the gel composition.

Microbiological research on microemulsion composition development with anti-inflammatory and antimicrobial action

Microbiological research on microemulsion composition development with anti-inflammatory and antimicrobial action

Atomization behavior of burning stable emulsion droplets

We investigate the atomization behavior of burning stable water-in-oil microemulsion droplets. The microemulsion compositions are prepared by altering the dispersed phase volume fraction (ϕ) and base oils (dodecane, xylene, and surrogate (90% dodecane and 10% xylene) by weight). The combustion of base oil follows classical droplet combustion, while two-stage combustion, i.e., classical droplet combustion and atomization-dominated combustion, is observed for emulsion droplets. We reveal that vapor bubble formation occurs primarily through heterogeneous nucleation, and the mechanisms leading to bubble formation can be accurately predicted and controlled for distinct, highly stable emulsions. During the initial phase of combustion, water vapor bubbles nucleate, while the nucleation of oil vapor is more prevalent in the later phase of combustion due to the depletion of water content. In both regimes, heterogeneous nucleation ensues due to the agglomeration of surfactant inside the burning droplet. The lower volatility and viscous nature of the oil inhibit the growth rate of the nucleated oil-vapor bubble within the oil–surfactant mixtures. On the contrary, the water vapor bubble exhibits a higher growth rate within the emulsion droplet, attributed to its higher volatility and low viscosity. We show that qualitatively, the global bubble dynamics associated with the emulsion droplets remain substantially consistent regardless of ϕ and the type of base oil. However, it is observed that the onset of nucleation, bubble growth and collapse cycles, and the size of secondary droplets display a strong dependence on the ϕ and the type of base oil. The normalized diameter at the onset of nucleation increases as ϕ increases, exhibiting a logarithmic trend. The optimal dispersed phase volume fraction for effective atomization is found to be ϕ=0.2, regardless of the type of microemulsion.

DISPLACEMENT OF OIL BY MICELLAR SOLUTION WITH NANOPARTICLES FROM POROUS MODEL WITH CORE MATERIAL

Enhanced oil recovery (EOR) techniques play an important role in maintaining oil production worldwide. These methods are given special attention due to the constant decline in the availability of oil resources. One type of EOR is the tertiary method - a chemical method that involves the use of synthetic substances for mining. Liquid flooding in the presence of a surfactant is a common chemical EOR, and microemulsions belong to these systems. The injection of the microemulsion rim reduces the interfacial tension between the crude oil and the formation fluid, which results in the mobilization of a significant portion of the residual oil. Recently, the possibility of simultaneous use of nanoparticles and chemicals to increase the efficiency of the processes of increasing oil recovery has been considered. In this work, nanoparticles participate in the role of microemulsion stabilization, and their joint effect on the displacement capacity of oil from the bulk model of a porous medium is also analyzed. The work is aimed at studying the effect of adding silicon oxide nanoparticles to a microemulsion solution, which is an agent for displacing viscous oil from a bulk porous medium. In the experiment, laboratory studies of oil displacement by various compositions, including surfactants, salt, alcohol and nanoparticles, were carried out on two types of bulk models assembled from glass beads and quartz sand, phase saturations were determined at different points in time, and displacement capacity graphs were built. The oil displacement study was carried out for six liquids: water, mineralized water, nanofluid, aqueous solution with surfactant, also a solution for microemulsion without and with the addition of nanoparticles. It has been found that the effect of adding nanoparticles to the microemulsion composition in the case of bulk models consisting of glass beads leads to a slight increase in the volume of displaced oil. In the case of bulk models consisting of core material, an increase in residual oil saturation is observed, which is associated with adsorption of particles on the surface of core material.

Perovskite-ICBA bulk-heterojunction thin films by slot die method: effect of microemulsion composition

Perovskite-ICBA bulk-heterojunction thin films by slot die method: effect of microemulsion composition

Application, structure, salts and complexes of lidocaine: a review. Part II. lidocaine in the composition of deep-eutectic solvents, microemulsions and coordination compounds

The review focuses on lidocaine (2-(diethylamino)-N-(2,6-dimethylphenyl)acetamide), one of the most popular and widely used painkillers. In the first part, the use of lidocaine in various branches of medicine was considered, and the structure of lidocaine, as well as of its salts such as hydrochloride monohydrate, hydrohexafluoroarsenate, bis-p-nitrophenylphosphate, barbiturate and indomethacin-lidocaine complex was discussed. The present paper reports on the use of lidocaine in the composition of deep-eutectic solvents (DESs) with acrylic acids, with such hydrogen bond donors as ibuprofen, 1,8-octanediol, tetracaine, prilocaine and vanillin, with such nonsteroidal anti-inflammatory drugs as ketoprofen, flurbiprofen, aceclofenac, tenoxicam and meloxicam. The use of lidocaine in DES-microemulsions (MEs) is also considered: lidocaine-prilocaine and lidocaine-ibuprofen prepared and served as the oil phase in ME, and lidocaine-lauric acid as an amphiphilic DES utilized as surfactant in ME. Consideration of lidocaine in the composition of coordination compounds has begun: the results of studying the structure of complexes of lidocaine with chlorides of zinc, copper, cobalt, platinum and iron, as well as with copper bromide, have been discussed.

Effective removal of paraffin deposits using oil-in-water microemulsion systems

This study investigates the effectiveness of using oil-in-water microemulsions, formulated with nonionic surfactant, for the removal of paraffin deposits. Experiments were conducted in a cylindrical steel cell, where a thin layer of paraffin was applied to the walls and exposed to various microemulsion systems. The microemulsions systems were formulated with kerosene (MESK), xylene (MESX), and diesel (MESD), and the removal efficiency was compared to that of pure solvents. Our results demonstrate that the efficiency of paraffin deposit removal using microemulsion systems is influenced by the concentration of both the active matter and oil component. Specifically, microemulsions containing kerosene in the oil phase exhibited the highest removal performance, with a removal efficiency of 66.78%, compared to 48.74% for pure kerosene solvent. Furthermore, our findings suggest that high removal efficiency can be achieved with low concentrations of oil phase (2–6 wt%), making microemulsions a more environmentally friendly and safer alternative to the use of pure solvents. We observe that increasing the liquid volume in the tubular can lead to a reduction in removal efficiency due to the reduced fluid shear. Overall, our study provides important insights into the potential applications of microemulsion systems for paraffin removal, with implications for various industrial processes and environmental remediation efforts. The results highlight the importance of optimizing microemulsion composition to achieve optimal removal efficiency and promote the use of more environmentally friendly solvents in paraffin removal operations.

Preparation and quality evaluation of total flavonoids microemulsion of "Pueraria lobata-Hovenia dulcis"

The effective components of flavonoids in the "Pueraria lobata-Hovenia dulcis" drug pair have low bioavailability in vivo due to their unstable characteristics. This study used microemulsions with amphoteric carrier properties to solve this problem. The study drew pseudo-ternary phase diagrams through titration compatibility experiments of the oil phase with emulsifiers and co-emulsifiers and screened the prescription composition of blank microemulsions. The study used average particle size and PDI as evaluation indicators, and the central composite design-response surface method(CCD-RSM) was used to optimize the prescription; high-dosage drug-loaded microemulsions were obtained, and their physicochemical properties, appearance, and stability were evaluated. The results showed that when ethyl butyrate was used as the oil phase, polysorbate 80(tween 80) as the surfactant, and anhydrous ethanol as the cosurfactant, the maximum microemulsion area was obtained. When the difference in results was small, K_(m )of 1∶4 was chosen to ensure the safety of the prescription. The prescription composition optimized by the CCD-RSM was ethyl butyrate(16.28%), tween 80(9.59%), and anhydrous ethanol(38.34%). When the dosage reached 3% of the system mass, the total flavonoid microemulsion prepared had a clear and transparent appearance, with average particle size, PDI, and potential of(74.25±1.58)nm, 0.277±0.043, and(-0.08±0.07) mV, respectively. The microemulsion was spherical and evenly distributed under transmission electron microscopy. The centrifugal stability and temperature stability were good, and there was no layering or demulsification phenomenon, which significantly improved the in vitro dissolution of total flavonoids.

Microemulsions as the Potential Delivery System for Nimodipine

Abstract An important area of interest in pharmaceutical technology is the issue of poorly soluble drugs and their formulation into drug dosage forms that ensure optimal bioavailability. One of the options to solve solubility is the development of nanodispersion systems. This work is focused on the preparation of microemulsion systems suitable for poorly soluble drugs, for example, nimodipine. The composition and structure of microemulsion enable solubilization of different drugs and make it a universal drug carrier. Microemulsions increased the solubility of the model drug 20-fold compared to solubility in water. The use of mucoadhesive polymers – hydroxyethyl cellulose and xanthan gum – improved the in vitro release significantly. The highest amount of nimodipine was released from the microemulsion gel system with hydroxyethyl cellulose (1% w/w) and this depended on the diffusion of dissolved molecules.

Investigation of transdermal permeation behavior of diclofenac sodium microemulsion by confocal laser scanning microscopy

Purpose: To investigate the in vitro skin permeation and transdermal behavior of diclofenac sodium using a new system of microemulsion. Methods: Diclofenac sodium was incorporated into oil-in-water (o/w) and water-in-oil (w/o) microemulsions consisting of a 2:1 ratio of Cremophor RH 40: Span 80 as surfactant phase, ethylhexyl palmitate as oil phase, and a 2:1 ratio of water: isopropanol as aqueous phase. Franz diffusion cell was used to determine the in vitro skin permeation. Morphology of microemulsions were characterized by transmission electron microscopy (TEM). The depth of penetration distribution was visualized by fluorescently labelling, and observing using confocal laser scanning microscopy (CLSM). Results: The o/w type provided an enhanced permeation flux, with more than a 3- fold increase in permeability coefficient across skin as compared with w/o type. The morphology characterization indicated that both o/w and w/o type were nano-sized and spherical in shape. It was observed by CLSM that o/w type significantly facilitated the penetration of sulforhodamine B (SRB) to the deeper layers of the skin (220 μm) than w/o type (150 μm). Conclusion: This study demonstrates that diclofenac sodium microemulsion can be transdermal, and the skin penetration depends on the microstructure and composition of microemulsion.

Mitigating exhaust emissions in CI engines using butanol-diesel-water microemulsions.

The current research work examines the usability of surfactant-free microemulsion fuels as a substitute in CI engines, with alcohol being used as an amphi-solvent. Studies were carried out on different compositions of microemulsions with 35% volume and 40% volume butanol, named ME35 and ME40, having 57.8-64.4% volume diesel and 0.6-2.2% volume water. Most of the microemulsions had properties such as viscosity, specific gravity, cloud point, and sulfur content comparable to those of diesel. The heating values and cetane indices of the microemulsions were 0.09-8.7% and 19.4-28.7% lower than diesel due to the addition of water and alcohol. The water and sediments percentages were found to be low, even after the addition of water, indicating the microemulsions were stable. ME40 showed an average of 0.6-3.5% improvement in BTE, but the BSFC was also increased by 5.3-8.9%. The emissions of HC, NOx, and PM showed an average decrease of 19.0-48.9%, 14.8-41.9%, and 10.06-50.24%, respectively, for all the microemulsions at all the loads. The CO emissions were lower at higher loads and vice versa, but the average CO emissions showed 5.16-31.9% decrease due to significant reductions at higher loads. It could, therefore, be concluded that microemulsions are a promising sustainable and cleaner substitute for diesel. Synopsis Microemulsion fuels successfully replaced up to 42% of diesel, with significant reduction in emissions of CO, HC, NOx, and PM.

Efficient extraction of phenol from wastewater by ionic micro-emulsion method: Anionic and cationic

Phenolic wastewater is one of the priorities in the field of wastewater treatment, which poses a serious threat to the human health and nature environment. In this paper, cationic cetyltrimethylammonium bromide (CTAB) and anionic sodium oleate (NaOL) microemulsions were utilized to extract phenol from the wastewater. The optimal extraction factors were investigated by exploring the effects of microemulsion composition ratio and extraction conditions on the phenol extraction performance. Furthermore, the enhanced extraction mechanism of phenol by cations microemulsions is illustrated by studying the extraction process of cationic and anionic microemulsions in the extraction of phenol. The optimum components were obtained: surfactant concentration of 0.2 mol·L–1, isoamyl alcohol volume of 30%, internal aqueous phase concentration of CTAB microemulsion of 0.05 mol·L–1, and internal aqueous phase concentration of NaOL microemulsion of 0.09 mol·L–1. The extraction efficiencies were 96.44% and 82.0% when using CTAB and NaOL microemulsions under optimal conditions (water–emulsion ratio of 5, contact time of 9 min, extraction temperature of 298.15 K, and pH of 9), confirming the enhanced extraction of phenol by CTAB cationic microemulsion. It was analyzed that the enhanced extraction of CTAB microemulsion was due to the electrostatic adsorption of cations with phenol root ions.

Microemulsions based on peony (Paeonia suffruticosa Andr.) seed oil and its fatty acids: Product development and stability enhancement

Peony (Paeonia suffruticosa Andr.) originated in China and has long been popular worldwide as an ornamental crop. In recent years, peony seed oil (PSO) as edible oil has received extensive attention due to its richness in unsaturated fatty acids, especially α-linolenic acid (ALA). In this work, fatty acid mixture-1 (FAM-1) and fatty acid mixture-2 (FAM-2) with different ALA concentrations were prepared from PSO by saponification and freezing crystallization. Pseudo-ternary phase diagrams were constructed to determine the composition and proportions of microemulsions (MEs), which were used to embed PSO and FAM. Based on pseudo-ternary phase diagrams, PSO ME prepared possessed a droplet size of 54.6 nm using a mixture of Tween 80 and Span 80 as the surfactant, while FAM-1 ME and FAM-2 ME owned droplet sizes of 30.1 and 29.7 nm using Tween 20 as the surfactant, respectively. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) analysis confirmed that the MEs had good dispersibility, and rheological analysis demonstrated excellent resistance to shearing rate changes. Besides, three MEs all exhibited good stability at 4 °C by microemulsification during the 60-day storage period in terms of droplet size, pH, and electrical conductivity. The water solubility and viscosity exhibited by the three synthetic MEs showed large potential to expand the application in cosmetics, medicine, and food industry.

Interfacial properties of liquid metal immersed in various liquids

HypothesisWhen gallium-based liquid metal (LM) droplets are injected through different solvent media, the oxygen solubility of the environment influences the droplet eccentricity. The formation of an oxide membrane in solvents can determine whether a bulk-scale droplet behaves in a liquidlike or solidlike manner. In the case of LM emulsions, the solvent’s oxygen solubility leads to varying degrees of organic solvent adsorption. The adsorption of solvent molecules changes the surface energy of the oxide layer. ExperimentsThe pinch-off frames of LM droplets immersed in liquids with differing oxygen solubility were captured using a high-speed camera. Through scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS), the surface composition of micro and nanoscale LM emulsions in different solvents was investigated. The van Oss-Good model was implemented to determine the polar and nonpolar surface energy components of LM layers with adsorbates. FindingsPear-shaped LM droplets displaying solidlike behavior are created when the mole fraction of dissolved oxygen in the ambient solution is above approximately 2.43×10-4. For LM emulsions sonicated in organic solvents, Carbon/Oxygen (C/O) and Carbon/Gallium (C/Ga) atomic percent ratios display an increasing trend with increasing oxygen solubility. The nonpolar component of surface energy shows a logarithmic relationship with the oxygen solubility of the solvent used to treat the LM layer. The polar component of surface energy is more susceptible to the chemical properties of the solvent.

Neem oil as natural pesticide: Pseudo ternary diagram and computational study

Bitter principles of neem oil have proven activity against agricultural pests. The neem oil is also reported for its potential insecticidal and mosquito repellency properties. As active principles of a non-edible neem oil cannot be separated from oil itself, formulating microemulsions of neem oil have a promising future. Microemulsions are preferred over conventionally used pesticide systems like for their long-term thermodynamic stability, safety, low viscosity, cost economy and aesthetic appeal. A pseudo ternary diagram is a convenient way of determining the compositions of the stable microemulsions and macroemulsions. By identifying specific regions in such plots, possible economical compositions can be determined. Such compositions use optimum quantities of surfactants. Moreover, our molecular docking analysis of an active principles of neem oil against odorant binding proteins, viz. 3N7H and 3Q8I suggested that compound, nimbin had higher binding affinities towards OBPs with docking scores of −87.4861 and −105.696 ​kcal/mol than their corresponding reference ligands. Thus, for a safer, an effective and an economical designing and developments of natural mosquito repellents, this study can be considered useful.

Insight into the surface composition of bimetallic nanocatalysts obtained from microemulsions

The enhancement of catalysts efficiency of bimetallic nanoparticles depends on the ability to exert control over surface composition. However, results relating surface composition and feeding solution of bimetallic nanoparticles synthesized in microemulsions are controversial and apparently contradictory. In order to comprehend how the resulting surface can be modified under different synthesis conditions and for different pairs of metals, a computer simulation study was carried out. The resulting surface compositions are explained based on the relative rates of deposition of the two metals, which depend on the particular metal pair, the concentration of reactants and the microemulsion composition. This study provides a satisfactory understanding of experimental results and allows us to identify the main factors affecting the nanoparticle’s surface composition. Consequently, concrete and practical guidelines can be established to facilitate the experimental synthesis of bimetallic nanoparticles with tailored surfaces.

Multi-Element Determination of Trace Elements in B7-diesel Oil by High-Resolution Continuum Source Flame Atomic Absorption Spectrometry

In this work, a method for sequential multi-element determination of Cu, Fe, Ni, Pb, Zn, Al, Cr and Sn in B7-diesel oil samples by high-resolution continuum source flame atomic absorption spectrometry (HR-CS F AAS) was proposed. The sample preparation was based on formation of microemulsion (ME), which was investigated through a three-phase diagram. The ME composition adopted was B7-diesel oil (3.3 g), aqueous phase containing nitric acid (1.4 mol L-1, 300 μL) and n-propanol (up to 10 mL). The use of surfactant Triton X-100 in the formation of ME was also evaluated. Limits of detection in the range of 0.01 – 0.4 mg kg-1 were obtained. Spike-recovery tests were accomplished and the results varied between 93 and 124%. The accuracy of the proposed method was confirmed by the analysis of certified reference material (CRM) NIST SRM 1084a (Wear-Metals in Lubricating Oil); there was no statistical difference between the obtained results and the certified values (at 95% confidence level). Twelve B7-diesel oil samples were analyzed and Cu, Fe and Cr were found in three samples. The proposed method was simple, fast and accurate. The sequential multi-element determination of trace elements presented advantages as low costs and reduction in analysis time, being appropriate for routine analysis.