The equipment detected all metals present in the sediment sample. Among these metals, chromium represented The determination of chromium concentration in aqueous solutions was carried out before and after the microemulsion extraction using a Varian Spec-trAAPlus atomic absorption spectrophotometer. All experiments, including the characterizations of the microemulsions, were performed in duplicate.
The composition of the coconut oil used in the experiments and the saponification reaction employed to obtain the saponified coconut oil SCO are described in Castro Dantas et al. The microemulsion system was composed of SCO as anionic surfactant S , 1-butanol as co-surfactant C , kerosene as the oil phase OP , and chromium sludge solution as the aqueous phase AP.
Design and Evaluation of Microemulsion Gel System of Nadifloxacin
A pseudo-ternary phase diagram with all Winsor regions was obtained in accordance with Castro Dantas et al. Two extraction methods were tested. The first one, Method A, consisted of mixing predefined quantities of chromium sludge solution acid digestion solution diluted in water and pH adjusted to 3. The second one, Method B, consisted of mixing predefined quantities of the same constituents until a phase separation was obtained in the WIII region microemulsion phase in equilibrium with aqueous and oil phases in excess.
After the determination of the Winsor systems inside the pseudoternary phase diagram, four points in WII and four points in WIII regions were selected to evaluate chromium extraction, effective size of the droplets, optical microscopy, and viscosity. The extraction percentages were calculated by using the following equations:. After the extraction process, a re-extraction process was performed to recover the chromium from the chromium-bearing microemulsion phase. The re-extraction process was made by adding 6 mL of a 10 M HCl solution to the chromium-bearing microemulsion phase. The presence of hydrochloric acid reduced the hydrophilicity of the surfactant, allowing the formation of a new aqueous phase rich in metal.
The re-extraction percentile RE Cr was calculated by using the following equations:. According to Moulik and Paul , measurements of viscosity are crucial when studying fundamental physicochemical reactions in colloidal dispersions. These data can provide first hand information on the internal consistency of colloidal dispersions, as well as furnish knowledge on the overall geometry of the particles of the dispersed phase. In this study, a Haake Mars rheometer was used to measure all viscosities.
This study determined the droplet size for systems with two- and three-phase regions. The characterization of particle size correlated size with the distribution of micelle droplets. The diameters of the droplets and their distribution in the microemulsions investigated were determined by using a dynamic light scattering particle analyzer Microtrac Granulometer - Nanotrac and the microtrac FLEX application software program.
Winsor II two-phase and Winsor III three-phase microemulsions were evaluated by optical microscopy Olympus BX51M , and the behavior of the phase separation was identified by using a 50x magnification. The active matter and the oil phase were placed in a Petri dish, according to the experimental composition of the studied system. The required amount of digested acid solution wt. The dynamic behavior of the phases was observed through the microscope when the chromium solution was added.
The first step in this research was to obtain the Winsor regions inside the pseudo-ternary phase diagram Figure 1.
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Based on work conducted by Castro Dantas et al. One can observe that the WII and WIII regions are present in the water-rich side, in the oil-rich side, and in the central portion of the pseudo-ternary phase diagram. As explained in the Experimental section, the chromium extraction used Method A to evaluate the results.
Nanoemulsions: formation, properties and applications
Table 1 shows the composition of the evaluated points and the results for chromium recovery. All systems showed very similar extraction behavior, which indicates that the shape of the micelle and the proportion between the oil and water phases are not determining factors in chromium extraction. Systems within the WIII region were considered appropriate because a chromium-rich microemulsion was obtained with a lower volume and with excess oil after the extraction process.
Considering chromium extraction and economic factors, Point 4 represents the best choice.
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After the extraction process, a re-extraction step was performed. The results for re-extraction are shown in Table 1. These systems were selected from the water-rich, the oil-rich, and the central portion of the pseudoternary phase diagram. The goal was to observe the behavior of micellar aggregates with varying proportions of oil and water. According Sripriya et al.
Microemulsions: Properties and Applications. Surfactant Science Series, Volume 144.
Thus it is mainly used to monitor the microstructure of the system. One can observe that low viscosity values were obtained for all studied systems. For WIII microemulsions, the oil phase had a major influence on the results. For WII systems, it was not possible to observe a general trend. Considering the microemulsion volume after chromium extraction, Point 4 represents the best choice. The main benefit of using radiolabeled compounds in drug development is to be sensitive and detectable for minimal amounts.
The development of powerful radiotracers requires careful consideration in the selection of the radionuclide. In this part, the example of radiolabeled microemulsions would be given. Ustundag Okur et al. Microemulsions have several advantages over microemulsion formulations when applied parenterally since they have fine particles and they are cleared more slowly than the rough particle emulsions resulting to have an extended staying time in the body.
Controlled release could be advantageous for parenteral formulation because it offers an advantage of decreasing the frequency of injection. Intravenous formulations with prolonged activity have medical and economic importance and the physicians are concerned with keeping therapeutic concentrations over long time and decreasing the number of applications. In addition; when considering economically, only well-educated person can apply intravenous administration, and if frequency of application is decreased, the cost of treatment is reduced and time is protected. Therefore new drug delivery system can be advisable for DOX to reduce the food and drug interaction and improve the bioavailability.
Based on the in vitro cell culture studies the authors suggest this dosage form as a promising alternative for oral drug delivery of DOX. According to the published paper, gamma scintigraphy studies were indicated that 99mTc-APT solution show two times higher uptake than 99mTc-APT loaded microemulsion in kidneys. The cells were incubated with radioactive samples during min. Permeability results showed that 99mTc-ALD microemulsion was more permeated from apical to basolateral when compared to basolateral to apical directions and 99mTc-ALD solution.
The role of gamma scintigraphic methods is well recognized for developing new drugs and detecting the biodistribution of medicines. Radionuclides also use to assess the permeability of microemulsion with in vitro cell culture studies. Obtained from the studies based on the results; microemulsions enhance the solubilization capacity and dissolution efficiency of poorly soluble drugs and drug solubilization capacity and dissolution efficiency are reliant on the microstructure of the microemulsions.
Solubilized drugs may influence the boundaries of structural regions and the transition point between different microemulsion microstructures. Microemulsions have been shown to be able to control drug delivery, increase drug solubility, increase bioavailability and reduce side effects. Mechanism of formation and structure of micro emulsions by electron microscopy. J Phys Chem. The definition of a microemulsion. Colloids Surf. A brief introduction. In: Najjar R, editor. Microemulsions: A novel approach to enhanced drug delivery.
Recent Pat Drug Deliv Formul. Colloids in drug delivery part of surfactants science series vol. Phase structure of microemulsions. Curr Opin Colloid Interface Sci. Microemulsions as delivery systems. Long-term stability, biocompatibility and oral delivery potential of risperidone-loaded solid lipid nanoparticles. Int J Pharm. Lipid-based systems for the enhanced delivery of poorly water soluble drugs. Adv Drug Deliv Rev.
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Proteins, polysaccharides, and their complexes used as stabilizers for emulsions: Alternatives to synthetic surfactants in the pharmaceutical field. A review of multifunctional nanoemulsion systems to overcome oral and CNS drug delivery barriers. Mol Membr Biol. J Colloid Interface Sci. The effect of oil components on the physicochemical properties and drug delivery of emulsions: To cold emulsion versus lipid emulsion. The theory of diffusion in microemulsions. Handbook of Microemulsion Science and Technology. New York: Marcel Dekker Inc; Nanoemulsions: Formation, structure and physical properties.
J Physics. Industrial Applications of Microemulsions. Preparation and evaluation of flurbiprofen loaded microemulsions for parental delivery.
Transdermal permeation of apomorphine through hairless mouse skin from microemulsions. Transdermal delivery of ketoprofen using Microemulsions. Preparation and in-vivo evaluation of self-microemulsifying drug delivery system containing fenofibrate. AAPS J. Microemulsions for topical delivery of estradiol. Using microemulsions for drug delivery.