Thermal expansion is an important design parameter of materials, which should be taken into account when developing, producing and using products. To control this significant characteristic of new materials, it is necessary to develop equipment, methods and measurement procedures that take into account the novelty of the specific behavior of these materials. The production of specially shaped samples is the main limitation in thermal expansion measurements. This primarily applies to new materials (heterogeneous, composite, poorly processed) developed for special tasks. These factors necessitated the development of a method for measuring the temperature coefficient of linear expansion of products and materials with arbitrary sample shapes, which was not available in previous implementations of interferometric methods. An interference speckle dilatometer SD was developed for measuring samples with irregular shape in the temperature range from 200 to 400 K. When creating the speckle dilatometer SD, the speckle interferometry method was implemented to measure the elongation of samples with an irregular surface with nanometer sensitivity. Since this device has no analogues, a study was conducted on the uncertainty components arising when measuring the thermal coefficient of linear expansion of materials on this device. The analysis of the uncertainty components of the measurement of the thermal coefficient of linear expansion of materials on the speckle dilatometer SD was carried out. An experimental determination of the measurement uncertainty of the thermal coefficient of linear expansion of TCLE measures of arbitrary shaped samples was obtained using the SD speckle dilatometer. After research and initial certification, the developed measurement instrument was approved and included in the State Secondary Standard of the unit of thermal coefficient of linear expansion of solids in the range of values from 0.05 · 10–6 to 100.0 · 10–6 K–1 in the range of temperature values from 90 to 1,900 K.

   The article examines the prospects for the development of mass measurement systems in the low mass range (less than 1 g) based on the Planck constant. The focus is on new measurement methods, including watt balance with electromagnetic and electrostatic gravity compensation. These systems are based on fundamental physical principles and provide an opportunity to avoid the accumulation of errors specific to traditional methods of transferring a unit of mass through weights. The author describes in detail the principles of operation of watt balance, including design features such as the use of laser interferometers to measure displacements and voltage control systems. The article emphasizes the relevance of developing domestic low mass measuring systems in Russia, which is due to the need to improve the accuracy of measurements in such areas as analytical chemistry, biotechnology and nanotechnology. It is noted that the transition to methods based on fundamental physical constants will significantly improve metrological support, minimize errors and create a new generation of weighing equipment. The work carried out at VNIIM is aimed at developing and researching small mass measurement systems based on new principles that are not inferior in characteristics to the best foreign analogues. The author highlights the importance of calibrating such systems through standards of electrical quantities, which ensures their reliability and validity. The proposed solutions represent a significant contribution to the development of metrology.

   The article presents information on the development of new types of certified reference materials (СRMs) for the composition of individual alkyl carbonates and СRM for the composition of a multicomponent solution of alkyl carbonates in methanol, provided with metrological traceability to GET 208-2024. A description of the procedure for preparation and certification of СRMs is provided, including studies of material homogeneity and stability. The features of certification of a multicomponent solution of organic substances of the same homologous series are described. The certified characteristic of СRMs for the composition of alkyl carbonates is the mass fraction of the main component in the pure substance (from 99.54 to 99.97 %) with a relative expanded uncertainty not exceeding 0.25 %. The certified characteristic of СRM for the composition of a multicomponent solution is the mass concentration of individual alkyl carbonates in methanol (from 1.99 to 2.01 mg/cm³) with a relative expanded uncertainty of certified values of 1.5 %.

   The article describes the work on creating reference materials for the composition of tin, selenium and antimony solutions, which are solutions of pure tin, selenium and antimony in mineral acids packaged in polymer bottles. The development of reference materials was carried out in several stages: preparation of solutions from pure substances and their packaging, determination of the certified value and homogeneity assessment, and stability testing of reference materials. The certified characteristics of the reference materials “mass fraction” and “mass concentration of an element” were established by atomic emission spectrometry with inductively coupled plasma using equipment of the State Secondary Standard for Units of Mass Fraction and Mass (Molar) Concentration of Metals in Liquid and Solid Substances and Materials GVET 196–1. The developed reference materials have been entered into the Federal Information Fund for Ensuring the Uniformity of Measurements in the form of sets of GSO 12278-2023/GSO 12281-2023, GSO 12703-2024/GSO 12706-2024, GSO 12707-2024/ GSO 12710-2024, each of which consists of four types differing in the value of certified characteristics.

   Primary reference materials are reference materials for the composition of gas mixtures composition in cylinders under pressure produced on the reference equipment complexes of the State Primary Standard of Units of Mole Fraction, Mass Fraction and Mass Concentration of Components in Gas and Gas Condensate Media GET 154–2019. These primary reference materials (otherwise called transfer standards) are the highest accuracy standards in the Russian Federation. The primary reference materials are designed to transfer the unit of mole fraction of components from GET 154–2019 to secondary and other working standards, high-precision measuring instruments; to ensure the conduct of and participation in international comparisons; to implement the calibration and measurement capabilities of the Russian Federation. It would not be an exaggeration to say that primary reference materials play a key role in the implementation of traceability and metrological support for all gas analytical measurements. To date, primary reference materials were prepared in specialized aluminum cylinders of foreign production, the import of which turned out to be difficult. In order to replace foreign cylinders with cylinders of domestic producers for the production of high-precision gas mixtures, the study described in the article was conducted. The results of the development and production of three typesof reference materials for the composition of gas mixtures based on sulfur dioxide, hydrogen sulfide, carbonyl sulfide in nitrogen diluents gas with standardized accuracy characteristics corresponding to the status of primary standards were published: GSО 12364-2023, GSО 12365-2023, GSО 12366-2023.

   The practical significance of the work is to preserve and strengthen the technological sovereignty of the country by developing primary reference materials for the composition of gas mixtures in cylinders of domestic producers and maintaining the functioning of the metrological support system for gas analytical measurements in the absence of cylinders of foreign production.

   The research results can be of practical value for cylinder producers interested in improving production technologies.

   The requirements of regulatory acts, issued by the Federal Agency on Technical Regulation and Metrology (Rosstandart) regulate the using the certified reference materials (CRMs) in accordance with their expiration dates and validity and envisage the procedures to confirm the certified metrological characteristics after the their production. In the period from 1989 to 1995, the A. P. Vinogradov Institute of Geochemistry, Siberian Branch of the Russian Academy of Sciences, developed as single batches two multielement CRMs: Lake Baikal bottom silt (BIL-1 – GSO 7126-94) and Lake Baikal bottom sediments (BIL-2 – GSO 7176-95). For these CRMs, the metrological characteristics of 49 and 30 elements and components, respectively, have been certified, so for more than 30 years they have used as material patterns of bottom substance in chemical analysis and analytical control procedures. The present study focuses on summarizing the previously obtained and new data about the mineral and granulometric compositions, homogeneity of powders of each CRM as the basis for the stability of their certified metrological characteristics. New data on the mineral and granulometric compositions of these CRMs are in good agreement with the previously obtained data. Besides, the distribution homogeneity of 33 elements in the powders of CRMs, and the smallest representative probes for the same elements were evaluated experimentally; for remaining elements/components these parameters were assessed by the indicator elements. The stability of the certified metrological characteristics of the elemental composition of these CRMs, under conditions of natural aging, has also been demonstrated through statistical processing of measurements obtained by various analytical methods and techniques over the long-times. The shelf lives and validities for the targeted use of BIL-1 and BIL-2 CRMs, being unique in terms of their information content, having no analogues in Russia and being in demand in the field of state regulation to ensure uniformity of measurements in chemical analysis of sedimentary substance, have been extended.

   Determining the composition of air environments (workplace air, atmospheric air, industrial emissions into the atmosphere) is important for environmental safety. Measuring their composition indicators in automatic mode is a priority direction in the activities of enterprises. However, measuring the content of metals in automatic mode is currently a complex, time-consuming and expensive task. The first step to eliminating these shortcomings may be an analysis of the capabilities of available measurement methods and reference materials. The authors of the review article described a comprehensive approach to ensuring the quality and accuracy of the measurement results of metal content in air environments, implemented using methods and reference materials developed at the UNIIM – Affiliated Branch of the D. I. Mendeleyev Institute for Metrology. The bibliographic is based on regulatory documents in the field of monitoring the state of air environments, in particular, RF Government Resolution No. 1847, GOST R 8.960-2019, GOST R 70803–2023, GOST R ISO 15202-1-2023, GOST 12.1.005–88 and others (27 sources in total). An array of relevant methodological recommendations was analyzed, for example, PND F 12.1.1–99, MU No. 4574–88 and others. Separately, the methods for measuring metal content in air environments developed by the UNIIM based on the most available measurement methods for most laboratories – photometric, titrimetric. The article provides a clear idea of the comprehensive approach to ensuring the quality of measurements of metal contents in air environments. The review article is structured as a combination of actions: development of measurement methods and their certification, development of reference materials for certification of measurement methods and quality control of the measurement results, conducting tests to approve types of reference materials, conducting interlaboratory comparison tests to control the quality of sampling procedures and quality control of the measurement results of metal contents in air environments. The article is addressed to testing laboratories , including industrial enterprises and environmental monitoring. Detailed explanations provide an idea of the fact that the measurement methods developed by the UNIIM can be used to determine the content of metals (components) in various air environments: workplace air, atmospheric air, industrial emissions into the atmosphere. Users of the specified methods will be able to vary the measurement parameters taking into account the technical capabilities of the laboratory without deviating from the provisions of GOST 12.1.005–88, PND F 12.1.1–99.

   Metrological support of conductometric liquid analyzers in accordance with the State Verification Schedule for Means of Measuring Specific Conductivity of Liquids requires the use of certified reference materials. Analysis of information on certified reference materials in the Federal Information Fund for Ensuring the Uniformity of Measurements revealed the absence of reference materials of specific electrical conductivity of certified liquids with certified values over 20 S/m. It was necessary to determine the source material for developing test samples: the authors hypothesized that nitric acid solutions can be used as the basis for reference materials of specific electrical conductivity of liquids. The article presents the materials of the study of the metrological characteristics of aqueous solutions of nitric acid for their further use as a initial material in the development of reference materials used to transfer the unit of specific electrical conductivity of liquids to conductometric liquid analyzers. The result was the development of test samples of nitric acid solutions with a nominal value of specific electrical conductivity of 35, 50, 85 S/m and the subsequent assessment of their certified value, and the determination of the confidence limits of the relative error. The studied nitric acid solutions can be used to transfer the unit of specific electrical conductivity of liquids from the working standard of the 1^st and 2^nd categories to measuring instruments using the direct measurement method. The research materials can form the basis for future improvement of GET 132-2018 in terms of expanding the measurement range from 50 to 100 S/m. The article is addressed to metrologists engaged in verification, calibration and testing for approval of types of conductometric liquid analyzers. The published review of literary data may be useful for specialists of specialized institutes.

   The article presents an analysis of the state of metrological support in the field of alternating electric voltage measurements in the frequency range up to 30 MHz.

   The purpose of the work is to determine the required accuracy level for the further creation of secondary and working standards used in transferring the unit.

   Analysis of data from the Federal Information Fund for Ensuring the Uniformity of Measurements allowed systematization of key issues of the reference base, in particular, the difficulties of ensuring metrological traceability in the frequency range up to 30 MHz. The study examines issues of improving metrological support and formulates recommendations for ensuring the required accuracy of working standards and modernizing secondary standards. The research results, presented in tables and diagrams, made it possible to assess the current state of AC voltage unit reproduction and ensure the level of preservation of the hierarchy of the State verification schedule in the medium term for 5–10 years. The findings are of practical value for standardization and metrology centers, developers of measuring instruments, specialists in the field of verification and certification of secondary and working standards. The presented information may serve as a basis for the development and implementation of new serial high-precision measuring instruments by instrumentation enterprises and gives an idea of the potential for metrological equipment of various economic sectors with them.

   The Register of Approved Types of Standard Samples (SS) is intended for registration of SS, whose types are approved by the Federal Agency for Technical Regulation and Metrology (Rosstandart), and is presented in the section "Approved Types of Standard Samples" of the Federal Information Fund for Ensuring the Unity of Measurements (FIF UEM). The FIF UEM section on SS of composition and properties of substances and materials is maintained by the State Service for Standard Samples of Composition and Properties of Substances and Materials in accordance with Part 9 of Article 21 of Federal Law No. 102-FZ1. The Fund is established in order to meet the needs of citizens, society, and the state for objective and reliable information, in accordance with Part 1 of Article 20 of Federal Law No. 102-FZ, which is used for the purposes of protecting the lives and health of citizens, protecting the environment, protecting the animal and plant world, and ensuring the defense and security of the state, including economic security.