Conformity Assessment of a Substance or Material to standard or regulation norms. What to Know About Risks of False Decisions Due to Measurement Uncertainties
Features of Determining the Water Content in Transformer Oil By Gas Chromatography https://doi.org/10.22184/2227-572X.2023.13.1.42.47
The water content in transformer oil is one of the important indicators characterizing the state of internal insulation in high-voltage transformers. Water in the insulation system is present in several forms (bound, dissolved, emulsion, layered). Currently, of all the known methods for determining the water content in insulating liquids, only two allow measuring its total mass concentration. They are based on coulometric titration and gas chromatography. During the operation of high-voltage equipment, the complex chemical composition of the oil changes greatly. Compounds are formed in it that interfere with the determination of the target component – water. Therefore, when analyzing old oxidized oils, it is of great importance to select the optimal conditions for carrying out technological operations, which allow obtaining the most reliable result. The results of quantitative determination of water from operational (oxidized) oil under different chromatography modes are presented. The data of chromatographic analysis are compared with the results of water analysis by the Karl-Fischer method. The closest values of water concentration were obtained at an evaporator temperature regime of at least 320 °C, which differs from the conditions specified in the standard procedure.
Features and Directions of Development of the Laser Ablation Method for the Synthesis of Nano-Particles https://doi.org/10.22184/2227-572X.2023.13.1.48.54
The article presents an analytical review of the literature concerning the features of the laser ablation process for the synthesis of nanoparticles. The laser ablation method is shown to be promising, which makes it possible to meet the specified requirements for the characteristics of nanoparticles. The main factors affecting the obtained nanoparticles, such as laser parameters (source, wavelength, fluence, pulse duration and frequency), target material and geometric characteristics, and the state of the environment (liquid, gaseous medium, vacuum) are given. The development trends of the method are determined.
Exposome and Chemists https://doi.org/10.22184/2227-572X.2023.13.1.56.59
This article is an overview description of exposomics that is a concept and a modern field of biomedical and chemical-analytical research related to the study of the integrity of various exposures to a human body over a long time period. The complicated structure and components of an exposome are considered. The external and internal exposomes and their chemical components, including exogenous compounds, products of their biotransformation and endogenous metabolites, are identified. It is indicated that the development of exposomics in its chemical aspects is based on the use of nontarget chemical analysis techniques, including various variants of chromatography and mass spectrometry. The development of data science is characterized, the consequence of which is the emergence of numerous databases in which the relationship between various chemical compounds and certain diseases is outlined. The goals of exposomal research that are or should be carried out by analytical chemists, are formulated.
Development of an Express Method for Determining Total Sugar in Diabetic Confectionery https://doi.org/10.22184/2227-572X.2023.13.1.60.64
This article is devoted to the development of a simple express method for determining total sugar in diabetic confectionery products in order to introduce systematic control of products produced by food industry enterprises entering the shelves of chain stores, not specialized stores in the city. The generally accepted methods for determining sugar and reducing substances were studied; as a result, the principle of the ferricyanide method of analysis was used as the basis for the development of the modification. The work carried out the selection of the concentration of potassium ferricyanide, the alkalinity of the medium, the separation of interfering insoluble components, the selection of the concentration and amount of the indicator, the choice of the method of sampling for analysis. The developed technique was tested on popular diabetic confectionery products available for free sale. The technique is characterized by good reproducibility, reduces the total time of definitions and reduces their labor intensity by 3–4 times.