Use Of Micellar Systems Research Articles

Separation of 9-Fluorenylmethyloxycarbonyl Amino Acid Derivatives in Micellar Systems of High-Performance Thin-Layer Chromatography and Pressurized Planar Electrochromatography

The problems with separation of amino acid mixtures in reversed-phase mode are the result of their hydrophilic nature. The derivatisation of the amino group of mentioned above solutes leads to their solution. For this purpose, 9-fluorenylmethoxycarbonyl chloroformate (f-moc-Cl) as the derivatisation reagent is often used. In our study, the separation of some f-moc- amino acid derivatives (alanine, phenylalanine, leucine, methionine, proline and tryptophan) with the use of micellar systems of reversed-phase high-performance thin-layer chromatography (HPTLC) and pressurized planar electrochromatography (PPEC) is investigated. The effect of surfactant concentration, its type (anionic, cationic and non-ionic) and mobile phase buffer pH on the discussed above solute migration distances are presented. Our work reveals that the increase of sodium dodecylsulphate concentration in the mobile phase has a different effect on solute retention in HPTLC and PPEC. Moreover, it also affects the order of solutes in both techniques. In PPEC, in contrast to the HPTLC technique, the mobile phase pH affects solute retention. The type of surfactant in the mobile phase also impacts solute retention and migration distances. A mobile phase containing SDS improves system efficiency in both techniques. Herein, such an effect is presented for the first time.

ВПЛИВ ПОВЕРХНЕВО-АКТИВНИХ РЕЧОВИН НА ФЛЮОРЕСЦЕНТНІ ВЛАСТИВОСТІ ФЛУОРЕСЦЕЇНУ

The use of fluorescence as an analytical signal makes it possible to reduce the limits of detection of analytes. The study of spectral properties of luminophores is important for the development of new methods for analyzing various objects. The use of micellar systems enables to increase quantum yields by 2–10 times and fluorescence intensity by 3–80 times and reduce the limits of detecting analytes by 1–2 orders of magnitude. Organized media based on surfactants influence on the fluorescence of luminescent indicators and their complex compounds due to changes in their microspheric solution of their photophysical characteristics, aggregate state and microprobe nature. Cationic surfactants occupy a special place among cytotoxicants. Low levels of maximum permissible concentrations of cationic surfactants require the use of sensitive analytical methods that combine simplicity and availability with reliability and expressiveness. Known chemical and microbiological methods for the determination of cationic surface-active antiseptics, disinfectants and preservatives characterize by complexity and labor intensity and are not suitable for the operational control of their concentration in places of local use. Therefore, the purpose of the work was to study the influence of various types of surfactants on the fluorescence properties of fluorescein to develop a method for determining the content of ethonium. The influence of surface-active substances of different types on the fluorescence properties of fluorescein was investigate. The anionic surfactant almost does not effect on the intensity of the dye signal. Nonionic surfactant leads to a gradual decrease in the fluorescence intensity of fluorescein. The most visible influence was observe with adding into the solution cationic surface-active substances. There is harsh intensity decrease of the dye fluorescence with subsequent exit to the «plateau» in the system of fluorescein-cetylpyridinium chloride. The cationic surfactant ethonium works the same. Received results will laid in the basis of the method development of ethonium determination in the medical drugs.

Recent trends in the use of organized molecular systems combined with chromatographic techniques in environmental analysis

The establishment of new analytical methods which improve quality and sensitivity in the determination of environmental pollutants in liquid and solid samples is demanded. The use of micellar systems have become an advantageous tool for the extraction of pollutant compounds, due to their easy handling, biodegradability, and the one-step procedure, and they are compatible with the hydroalcoholic mobile phases used in HPLC. The focus of this review is to present recently developed methods and the main trends in the use of micellar media combined with solid-phase microextraction and solid-phase extraction in the chromatographic analysis of organic compounds in different types of environmental matrix, including water, sediments, and biological samples. Selected samples illustrate the benefits of these systems in the whole of analytical process. The advantages of micellar media over conventional extractants are reduction of solvent usage, low cost, easy handling, and non-toxic procedure.

The use of micellar systems in the extraction and pre-concentration of organic pollutants in environmental samples

Establishing simple, fast, low-cost, sensitive and selective analytical methods for extraction and determination of pollutants in the environment is one of the main lines of research in environmental chemistry. Recent studies have demonstrated that micellar systems (surfactant solutions) constitute a real alternative to organic solvents for use as extractants of organic pollutants from liquid and solid environmental samples. This article is an overview of the use of micellar systems in the extraction/pre-concentration of different organic pollutants. Specifically, it discusses the application of the cloud-point extraction (CPE) and microwave-assisted micellar extraction (MAME) methodologies to the extraction and pre-concentration of organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polychlorinated dibenzofurans (PCDFs), polychlorinated dibenzo- p-dioxins (PCDDs) and phenolic derivatives, from environmental matrices. These studies show the advantages of these optimised methodologies over the traditional extraction techniques.

The use of micellar systems in the extraction and pre-concentration of organic pollutants in environmental samples

The use of micellar systems in the extraction and pre-concentration of organic pollutants in environmental samples

Determination of Benzimidazole Fungicides by HPLC with Fluorescence Detection After Micellar Extraction

An analytical method was developed to determine the benzimidazole fungicides and their residues (benomyl, carbendazim, thiabendazole and fuberidazole) in real water samples. Analyses were performed by reverse phase (RP) HPLC with direct fluorescence detection with mobile phase methanol:water, 40:60 (v/v) with 0.6% (v/v) ammonia. The extraction of analytes from water samples was performed with the use of micellar systems. Specifically, oligoethylene glycol monoalkyl ether (Genapol X-080) and polyoxyethylene 10 lauryl ether (POLE) were used as extractants. The recoveries of fungicides obtained in spiked water samples ranged from 68% to 94% for Genapol and from 68% to 96% for POLE. The limit of detection (LOD) was lower than 6 μg L−1 for carbendazim, 7 μg L−1 benomyl, 0.15 μg L−1 for thiabendazole and 0.01 μg L−1 for fuberidazole in both surfactants.

Opportunities for process intensification using reverse micelles in liquid and supercritical carbon dioxide

Liquid and supercritical carbon dioxide can be used as a replacer for organic solvents, which potentially enables the development of clean processes. A general disadvantage of CO 2, however, is that it is a very poor solvent for high molecular weight or hydrophilic molecules. By using reverse micelles to overcome this problem, a wide variety of novel processes can be thought of. In this review, it is shown that the use of micellar systems in supercritical CO 2 leads to processes generating a minimum amount of waste and with a low energy requirement. It is also shown that especially downstream processing of biochemicals and polymerization reactions can benefit from this technique, as the number of consecutive process steps can be reduced significantly.

NMR INVESTIGATION OF THE SOLUBILIZATION OF A HYDROPHOBIC EXTRACTANT IN A CTAB/BUTANOL MICELLAR SYSTEM

ABSTRACT This work concerns the use of micellar systems or microemulsions as the extracting phase for metal ions in place of an organic solvent. It focuses on the solubilization in cetyltrimethylammonium bromide (CTAB)-butanol-water ternary systems, of an extractant of industrial origin : 7-(4-ethyl-l-methyloctyl)8-hydroxyquinoline (C11-HQ), obtained from Kelex 100. The presence of cosurfactant allows high incorporation of the extractant, which can be viewed as a microemulsification of oil in water. 1H NMR chemical shift, linewidth and relaxation time measurements have been used to determine the location of C11-HQ in the micelle pseudophase as a function of different parameters : concentration of C11-HQ, pH and the presence of metal ions. A novel feature is the evidence for a transition between a state where the extractant is essentially located in the amphiphilic palisade, to a state where it is located in the centre of the micelles. This transition occurs when the surfactant to extractant ratio becomes ...

Micellar catalysis in reaction-rate methods

The use of micellar systems in kinetic-based determinations involving catalysed and uncatalysed reactions is considered. The different strategies devised so far for increasing sensitivity and selectivity by using such systems are discussed in terms of the roles played by micelles in reaction-rate methods. The concurrence of micellar and chemical catalysis results in major advantages for new applications.

Use of Micellar Systems as Vehicles for Hercosett and Hydrogen Peroxide Finishing of Wool Fabrics

The use of micellar systems as vehicles for applying Hercosett resin and hydrogen peroxide on virgin wool has been investigated. For this purpose phase diagrams of micellar solutions with Hercosett resin and nucleophilic reagent were produced to determine the corresponding areas of monophasic solubility. The shrink resistance conferred to treated wool and the damage produced in the physico-chemical properties of keratin fibers have also been investigated.

Study of the derivatization of n-alkylamines with 1-fluoro-2,4-dinitrobenzene in the presence of aqueous cetyltrimethylammonium bromide micelles

The use of aqueous cetyltrimethylammonium bromide micelles in the derivatization of n-alkylamines with 1-fluoro-2,4-dinitrobenzene was investigated systematically. The rate constants of derivatization of the n-alkylamines (C 1–C 8) were analysed using liquid chromatography. Up to butylamine the micellar rate enhancement depends on the electrostatic interactions between the amines and cetyltrimethylammonium bromide, and beyond C 4 it depends mainly on the hydrophobic interactions. The reaction rates are also enhanced by a micelle-induced decrease of the p K a of the amines, but to a lesser extent. The derivatization rates for the longer alkylamines are comparable with those in dipolar aprotic solvents. Pharmaceutical and biomedical science is likely to benefit from the use of micellar systems in pre-column derivatization reactions in aqueous solutions.