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Employees of the Faculty of Chemistry of Moscow State University have developed effective extraction systems and methods for extracting food dyes. The work is published in the Microchemical Journal. Next up are proteins, vitamins, and steroids.

Extraction is a widely used method of separating, separating, and concentrating substances with a solvent. This is the most important stage in preparing the sample for analysis. Extraction is often used in modern chemistry due to its versatility, ease of execution, and availability of reagents. However, traditional organic solvents are volatile, flammable, and toxic. Therefore, chemists are constantly looking for new, environmentally friendly solvents.

The staff of the concentration laboratory of the Department of Analytical Chemistry of Moscow State University under the guidance of Professor Igor Pletnev developed effective extraction systems based on ionic liquids and selected the optimal parameters for the extraction of food dyes. "Our research is related to the study of a new generation of extraction systems-combined solvents. These are liquids whose existence requires the presence of at least two types of particles-molecules and ions, " said Svetlana Smirnova, Associate Professor of the Department of Analytical Chemistry, Ph. D. in Chemistry, one of the study participants.

The main advantage of combined solvents is their dual nature. It is quite difficult to regulate the properties of a conventional molecular solvent. In combined solvents, there is a unique possibility of directional change of properties through changes in the composition and nature of the components. This type of solvent includes ionic liquids – melts of organic salts, liquid at room temperature.

"As an alternative to the chemically inert and expensive classical ionic liquids, we have proposed very unusual hydrophilic-hydrophobic ionic liquids. They do not mix with water, they do not dissolve much in it, but the water itself dissolves well in them. It turns out that we are dealing with water-like organic solvents. The synthetic food dyes that we studied in our work are fully extracted in such systems, " added Svetlana Smirnova.

The main problem encountered in the determination of dyes is the problem of their quantitative isolation from complex systems. For example, some of the most popular pigments - sulfo dyes exist in aqueous solutions in negatively charged forms and therefore very poorly pass into a conventional molecular solvent. To convert them to an organic solvent, additional chemical reactions must be carried out. However, it is not always possible to achieve effective extraction. With ionic liquids, such problems did not arise, the authors managed to achieve quantitative extraction of dyes.

"The determination of dyes can be useful for assessing the quality of products, the pollution of environmental objects. In food products, the dye is found in high concentrations, and in wastewater from the food industry, it can be contained in low amounts. However, low levels still need to be controlled, because dyes can accumulate in the environment and harm the health of animals, impair the quality of water. In this case, it is necessary to concentrate the dye, because the sensitivity of the analysis method may not be sufficient for direct determination. The systems we work with allow us to extract a substance from a large volume of the aqueous phase using a small volume of solvent, " said Kristina Lyskovtseva, another participant of the study, a PhD student at the Faculty of Chemistry of Moscow State University.

In the future, the authors plan to continue studying the properties of the developed ionic liquids, as well as to look for new biocompatible, environmentally friendly and affordable solvents. Work is underway to identify biologically important compounds: amino acids, biogenic amines, vitamins, and steroid anti-inflammatory drugs.

Photo. Alexandra Kucherova/MSU

MSU Press Service, scientificrussia.ru