The development of new methods for the analysis of chemical markers in biological fluids is an urgent area of research, because it is focused on solving socially significant tasks related to healthcare, chemical safety of the population, and countering terrorism. In this regard, new methods for the analysis of metabolites and exogenous substances in the body using alternative biological fluids available for non-invasive sampling are being actively studied and developed. In this paper, the authors present the results of developing and testing an approach for express determination of micro concentrations of volatile organic substances in the lipid layer of human skin by gas chromatography/mass-spectrometry (GC/MS) using a simple procedure of non-invasive sampling without a sample preparation stage. Samples of the lipid layer were collected using adhesion arising from mechanical contact of a metal carrier made of a piece of wire with the skin’s surface, and were analyzed without any additional sample preparation. A field chromatograph-mass-spectrometer with a custom made attachment for introducing samples with flash thermal desorption, previously designed by the authors, was employed for performing analyses. The qualitative composition of trace impurities in the lipid layer of the skin was characterized in the samples collected from 25 donors during the approbation of the method; identified impurities included technological additives to common plastics, psychoactive substances, medicines. It was shown that the impact of sample size variability during sampling on the repeatability of analytical results can be significantly reduced by using one of the main matrix components (e.g., squalene, oleic or palmitic acid) as an internal standard. The analysis time, including sample preparation, did not exceed 15 minutes. The feasibility of using the proposed approach for therapeutic drug monitoring with a 5-minute analysis frequency was demonstrated using caffeine as an example. An increase in caffeine content in the skin lipid layer (relative to oleic acid) in the range of 0.02 % to 2 % was experimentally observed after consumption of caffeine; the pattern of concentration changes differs significantly for different modes of consumption.
The contribution of Rostov-on-Don X-ray physicists (Professor M.A. Blokhin's school) to the development of theoretical foundations and practical techniques for applying X-ray spectral analysis (XRSA) is considered. The review provides a detailed examination of the peculiarities of XRSA specialist training at Rostov-on-Don State University (Southern Federal University from 2006) and the organization of XRSA research work in Rostov-on-Don. In the initial period (1960–1970) the main attention was paid to testing the capabilities and improving the analytical methods that were novel for that period. These were the Beattie-Brissi method, the calibration method, the standard-background method, and the additives method. Subsequently, research based on the application of theoretical assessment of matrix effects in XRSA (assessment of the contribution of selective excitation to the intensity of analytical lines, assessment of the influence of sample heterogeneity and options for accounting for this influence on the intensity of analytical lines for some practical cases, application of the theoretical correction method) became a priority. Other directions, such as the use of proton- and ion-excited X-ray spectra; the development of equipment for XRSA variants with total external reflection of primary radiation; and the practical application of energy-dispersive spectrometers with secondary emitters, were developed. The contribution of the Rostov University’s Basic Research Laboratory of X-ray Spectral Analysis staff to the development and implementation of automated analytical control systems at non-ferrous metallurgy enterprises is noted. The contribution of the research groups led by M.A. Blokhin, N.F. Losev, and their students, V.F. Volkov, V.I. Chirkov, Sh.I. Duimakaev, V.V. Druz, Yu.I. Velichko, V.P. Krasnolutsky, A.L. Tsvetyansky, and M.I. Mazuritsky is briefly discussed. Rostov-on-Don X-ray physicists, graduates of Rostov State University (and Southern Federal University) have worked in scientific and industrial laboratories throughout the Soviet Union, and currently continue to work in Russia and other countries.
Organic carbonates of linear and cyclic structure are widely used as "green" solvents, reagents or additives in organic synthesis and polymer chemistry. Organic carbonates have found their main application as electrolytes for lithium-ion batteries. The organic carbonates do not have toxic properties, however when released into the atmosphere they undergo photooxidation forming substances harmful to the environment (carbon mono- and dioxide, formaldehyde, etc.). Methods of determination in working area air have been developed for some organic carbonates. Large-scale production and use of organic carbonates leads to pollution of air, waste and natural waters, and soils. The aim of this work is to study the methods of extracting linear and cyclic carbonates from solid media (sand, soil) with subsequent gas chromatographic determination. Head-phase extraction was used to extract linear carbonates; extraction with an organic solvent with subsequent concentration was employed in case of cyclic carbonates. The conditions for performing extraction were determined. The limits of determination were (1–2) µg/g for linear and (8‒10) µg/g for cyclic carbonates. The methods of determination are simple, rapid, and the measurement error does not exceed 10 %. Studies of the residual content of organic carbonates in soil after exposure to open air at 25 °C and 35 °C were conducted. It was established that linear carbonates are released from the soil at the highest rate. Cyclic carbonates do not pass into the gas phase; they remain in the solid matrix and undergo chemical transformation. Increasing temperature from 25 °C to 35 °C does not affect the process of decreasing the content of cyclic carbonates in soil but only affects the removal of linear carbonates.
The effect of composition of canned fruits and vegetables on chromatographic separation of azo-, triphenylmethane, and indigo carmine dyes currently approved for use in the Russian food industry was studied. The study was carried out on a Shimadzu liquid chromatography instrument as a part of efforts to develop a regulatory and technical framework for the control of artificial dyes in food products. The conducted studies revealed the presence of undeclared synthetic dyes in ketchup, which, also according to the Technical Regulations of the Customs Union “Food products in terms of their labeling” (TR 022/2011, effective from July 1, 2013), the manufacturer is obliged not only to indicate, but also to give the following warning to buyers: “It contains a dye that can have a negative effect on children's activity and attention”. The study also showed the need to develop and disseminate new state standards for more types of food products.
Aliphatic (fatty) acids and closely related lipids of various structures constitute the most extensive group of organic compounds in plants, which can act as markers of the physiological state and the degree of reaction of environmental factors on plants. To determine aliphatic carboxylic acids (C12-C24) in plant materials we proposed an approach that combines the stages of the acids’ extraction and derivatization in methanol (one-step extraction/methylation method) followed by determination of the resulting esters by gas chromatography with a flame ionization (GC-FID) or a mass spectrometry (GC-MS) detector. Optimization of acid extraction from plant samples and their methylation was carried out using the following parameters: the mass ratio of the extractant and the sample during extraction, the concentration of hydrogen cations (catalyst), the duration of extraction, and the temperature of the reaction mixture. It was shown that the degree of extraction of fatty acids and lipids from a plant sample under the selected optimal conditions reaches 97–99 %. A method for determination of fatty acids (C12–C24) in plant materials was developed. The range of determinable contents is 0.005–0.5 mg/g, the relative error is 15–20 %, the sample weight is 0.2–0.25 g, the total analysis duration is 2.5 hours. The qualitative and quantitative composition of fatty acids in medicinal plants – hyssop (lat. Hyssopus officinalis) and motherwort (lat. Leonurus cardiaca) – was assessed. Ten carboxylic acids were identified in the medicinal plants studied, i.e. seven saturated (dodecanoic, tetradecanoic, hexadecanoic, octadecanoic, eicosanoic, docosanoic, and tetracosanoic) and three unsaturated (octadecenoic, octadecadienoic, and octadecatrienoic). Hexadecanoic and linolenic acids are found in the highest quantities in plants of the Lamiaceae family.
