I. A. Platonov

Evaluation of the efficiency of volatile organic compounds extraction from eucalyptus viminalis (Eucalypti viminalis Labill) using subcritical extractants

Bioactive compounds were extracted from Eucalyptus viminalis with subcritical water in the temperature range of 120–200°C under a pressure of 5 MPa, as well as with aqueous solutions of ethanol with different concentrations at 200°C and 5 MPa. The resulted extracts were analyzed by gas chromatographymass spectrometry. The detected volatile organic compounds were identified. The contents of α-pinene, β-pinene, α-phellandrene, p-cymene, and 1,8-cineole in the extracts obtained were determined.

Subcritical water extraction of biologically active substances from milk thistle seed (Silybum murianum L.)

A method of subcritical water extraction (SCWE) of biologically active substances from milk thistle seed (Silybum marianum L.) that makes it possible to obtain aqueous extracts without using organic solvents is suggested. The contents of hepatoprotective biologically active substances (taxifolin, silychristin, silydianin, and silybin) in milk thistle seed extracts obtained by SCWE and by standardized liquid extraction procedures are compared.

Improved approach towards synthesis of adamantane-1,3,5-triol

Abstract1-Adamantanol can be converted into adamantane-1,3,5-triol in the presence of N-hydroxylphthtalimide, cobalt(II) acetylacetonate, and manganese dioxide under oxygen atmosphere in glacial acetic acid.

Potassium fluoride as a selective moisture trapping agent for SPE-TD-GC-FID determination of volatile organic compounds in air

Anhydrous potassium fluoride has been proposed as a novel selective moisture trapping agent for gas chromatography to remove water vapor during adsorption concentration of low molecular weight volatile organic compounds (VOCs) from moist air. Unlike the traditional desiccants, potassium fluoride does not adsorb alcohols and ketones. To improve the adsorption efficiency, the analyzed air stream was purged through two sequential traps. The first trap was filled with a desiccant based on potassium fluoride and the second trap contained a sorbent to retain low molecular weight VOCs such as methanol and acetone. The adsorption of VOCs was followed by a thermal desorption from the second trap into the gas chromatographic column for analysis with a flame ionization detector. The proposed moisture trapping and preconcentration assembly allows determination of low molecular weight VOCs at the levels of μg m−3 with RSD not exceeding 5% after 4–8 minutes of preconcentration.

Generating gas flows with a constant trace concentration of hydrogen sulfide

The dynamic gas extraction of hydrogen sulfide from aqueous solutions of sodium sulfide was studied theoretically and experimentally. The effects of the number of bubblers, the concentration of sodium sulfide, and the pH of solution on the concentration of hydrogen sulfide in the generated gas flow were found. The proposed method for generating gas flows with a constant trace concentration of hydrogen sulfide can be used for calibrating the verifying instruments for gas analysis.

Extraction of biologically active compounds from medicinal plant raw material by extractants in subcritical state

Extraction of biologically active compounds (BACs) from the medicinal-plant raw material “leaves of eucalyptus viminalis” (Eucalypti viminalis Labill) was performed by traditional methods, by sub-critical water at temperatures of 120 ± 1, 160 ± 1, and 200 ± 1°C and pressure of 5.0 ± 0.1 MPa in a dynamic mode, and extraction by 10, 50, and 70% ethanol solution in water at a temperature of 200 ± 1°C and pressure of 5.0 ± 0.1 MPa was performed. The qualitative and quantitative composition of the extracts were studied using methods of gravimetry, UV and IR spectroscopy, and reversed-phase high-performance liquid chromatography. The dependence of the extraction efficiency of BACs of eucalyptus viminalis on the type of extraction type was established.

Chromatographic properties of a capillary column with the Aerosil modified with nematic 4-methoxy-4′-ethoxyazoxybenzene

The chromatographic properties of a SCOT capillary column with the Aerosil modified with a nematic liquid crystal of 4-methoxy-4′-ethoxyazoxybenzene were studied. The Rohrschneider constants and retention factors were determined for substances from various classes. The microheterogeneous adsorbent SCOT(SiO2 + MEAB) belongs to medium-polarity stationary phases by its selectivity. It was shown that, in the temperature range 95–110°C, the studied column possessed high values of para-meta selectivity, efficiency, and capacity with respect to arenes and polar substances. Examples of rapid separations of mixtures containing isomers of different types are presented.

Hydrothermal synthesis of nanosize phases based on non-ferrous and noble metals

Research is devoted to reactions of binary complexes containing noble (platinum, palladium) and non-ferrous (cobalt, chrome) metals. Reactions proceed under hydrothermal conditions by the autoclave technique. Initials complexes and products of autoclave thermolysis were characterized by the FT-IR spectroscopy, the transmission electron microscopy (TEM) and the energy-dispersive X-ray spectroscopy (EDX). Comparative catalytic experiments in the test reaction were conducted. The obtained results can form the basis of new methods of nanosize multicomponent phases synthesis under hydrothermal conditions.

Gas chromatography of the future: columns whose time has come

Currently a new technology for the manufacture of chromatographic columns is being developed on the basis of methods designed to create microelectromechanical systems. This technology allows reducing the column size and also opens up prospects for developing a unique process for manufacturing columns without human intervention. The review presents data on the use of this technology for manufacture of gas chromatography capillary columns. The methods for preparation of capillaries and the influence of their shape and configuration on the chromatographic properties of the columns are considered. The methods for stationary phase introduction into capillaries, both traditional for capillary gas chromatography and borrowed from the semiconductor and microelectromechanical technologies are discussed. The unique properties of semi-packed columns obtained using microelectromechanical techniques are considered. The possible applications of such columns and the ways of their further development are discussed.The bibliography includes 179 references.

Caprolactam and nitrobenzene desorption from polymeric sorbents by subcritical water

Subcritical water is tested as an agent for caprolactam and nitrobenzene desorption from the hyper-cross-linked polystyrene sorbents MN-202 and MN-270. The efficiencies of desorption of these two compounds by subcritical water and by a water solution of isopropanol are compared.