Requirements for the accuracy and width of measurement ranges of shock accelerations increase as the production base in science and technology becomes more complex. In this regard, a relevant metrological task is to reduce errors in the verification and calibration of shock accelerometers. One way to increase the accuracy of shock acceleration measurements is to reduce the errors in reference means that arise when reproducing and transferring units of shock acceleration.

The reproduction of shock accelerations is implemented in many installations operating on different physical principles. However, none of the existing installations, nor a series of identical installations, can cover the entire range of peak acceleration values and pulse durations encountered in practice. Domestic metrological laboratories need a reference installation capable of covering the range of medium-intensity shock accelerations, which is widely required for verification and calibration of shock accelerometers, as well as for testing during the development and production of such equipment.

The objectives of the research are to develop, manufacture and test a shock installation mock-up that, after validation, could be used as a prototype of a reference shock installation for verification and calibration of shock acceleration transducers.

The starting point of the research was a review of the characteristics and capabilities of the State Primary Special Standard of the unit of acceleration during shock motion GET 57–84, working standards of the 2nd class (shock testing installation and vibration exciters operating in shock mode), and global analogues. Based on the analysis of literature data, an optimal scheme with a pneumatic piston was selected, implemented in the design of the shock installation for the secondary calibration method of accelerometers SE‑201 (manufacturer: SPEKTRA Schwingungstechnik und Akustik GmbH). Equipment used in the research: data acquisition module D002 (manufacturer: GTLAB LLC); charge conditioning amplifier NEXUS2692-A (manufacturer: Brüel & Kjær Sound and Vibration Measurement); accelerometer 1C301HA (manufacturer: GTLAB LLC). Methods of numerical simulation and numerical calculation, experimental and measurement methods were implemented. Software used: GTL (developed by GTLAB LLC); Ansys LS-DYNA (developed by ANSYS, Inc.).

Models of the hammer and anvil (two colliding bodies) with masses of 1 kg each made of hardened 40X steel were developed, manufactured and tested. Based on them, a shock installation mock-up was developed and manufactured. The results of numerical simulation of the impact interaction between the hammer and the anvil on the developed mock-up were experimentally confirmed: the shock installation reproduces the required shock pulse modes corresponding to a working standard of the 2nd class (peak shock accelerations in the range up to 10⁵ m/s² with pulse durations from 0.1 ms). The influence of plastic deformations of the hammer and anvil on the amplitude and duration of the shock pulse was estimated. Dependences of peak accelerations and pulse durations on the material and thickness of damping pads and on the drop height of the hammer are presented. Finally, the capabilities of the developed installation to serve as a prototype of a reference shock installation for verification and calibration of shock acceleration transducers are shown. In continuation of the topic described in the article, the author has planned research aimed at optimizing the hammer and anvil models, for example, reducing their weight. The influence of the geometry and mass of the anvil on its natural frequencies will also be studied. The possibility of incorporating a laser interferometer into the reference installation to provide calibration and verification by an absolute method is being considered.

Determination of GMO content in processed products of agricultural raw materials is an important task of analytical laboratories in the food industry. Measurements of the content of DNA sequences used in the construction of transgenic cassettes for food quality control have gained particular significance in international trade. Nucleic acid analysis methods, which require the use of reference materials, are applied for GMO content determination. The approval in 2024 of the State Primary Standard for the unit of DNA sequence copy number GET 220‑2024 has made it possible to begin the development of DNA composition reference materials certified for the ratio of DNA sequence copy numbers. In order to maintain metrological assurance of measurements performed in analytical laboratories, the development of reference materials most in demand for GMO analysis in the food industry has been carried out. Based on the tests performed, by the end of 2025 the following reference materials for GMO DNA composition were approved: for soybean lines A5547-127 (GSO 12963-2025 set GM-A5547-127-VNIIM), MON89788 (GSO 12961-2025 set GM–MON89788-VNIIM), A2704-12 (GSO 12962-2025 set GM-A2704-12-VNIIM) and for maize line MON88017 (GSO 12960-2025 set GM–MON88017-VNIIM). These reference materials replace existing foreign-produced reference material analogues and ensure metrological traceability of measurements performed in the Russian Federation in the field of GMO analysis to the State Primary Standard GET 220‑2024.

The article presents the results of the development of reference materials (RMs) for the isotopic composition of beet-derived and cane-derived sucrose. The work is conditioned by the need to ensure technological sovereignty and replace currently unavailable foreign certified reference materials (IAEA-CH‑6, UME CRM 1309) used to control the authenticity and geographical origin of food products (juices, alcohol, etc.) in accordance with the requirements of Russian and international standards. The developed method of RM preparation is described, including selection, purification, drying, grinding, and homogenization of raw materials with subsequent packaging. Isotopic composition measurements were performed on the Isoprime precisION isotope mass spectrometer using an elemental analyzer and a two-reactor system for simultaneous analysis of solid and liquid samples. The certified delta values of the isotope ratios of carbon (δ13CVPDB), hydrogen (δ2 HVSMOW) and oxygen (δ18OVSMOW) were determined, and the homogeneity, short-term and long-term stability of the RMs were investigated. The obtained values of δ13CVPDB correspond to the known literature ranges for C3 and C4 plants, which confirm the validity of the methodology. The values of δ2 HVSMOW and δ18OVSMOW for sugars have been certified for the first time. The developed RMs make it possible to ensure traceability of measurements to international scales; they are intended for metrological assurance of isotopic composition analysis in the food and chemical industries, scientific research, and customs control, as well as for conducting interlaboratory comparisons and certification of measurement procedures.

Until recently, the metrological assurance of measuring instruments for thermal analysis (synchronous thermal analyzers, mechanical analyzers, differential scanning calorimeters, Calvet calorimeters, thermophysical installations, and the like) in terms of measuring phase transition temperatures in the negative temperature range (from -150 to 0 °C) was carried out using resistance thermometers.

However, the design features of measuring instruments for thermal analysis limit the possibilities of their application. Such limitations include the high risk of damaging the measuring cell when attempting to place a resistance thermometer inside the measuring instrument. If the resistance thermometer is too close to the cell walls of the measuring instrument, temperature gradients occur. The limitations listed above, among others, have necessitated the development of reference materials.

The aim of this work is to validate pentane, octane, and hexane as candidate materials for reference materials for phase transition temperature, traceable to the State Primary Standards of the unit of temperature. The procedure for measuring phase transition temperatures (melting temperatures) was carried out using secondary thermometry with a first-class standard resistance thermometer. When determining the certified value of the reference material, the uncertainty contributions from the heterogeneity of the initial materials were evaluated, and the short-term and long-term stability of the materials were investigated.

The obtained metrological characteristics of the studied candidate reference materials for phase transition (melting) temperature are as follows: the range of permissible certified characteristics of the phase transition (melting) temperature for pentane is from -133 to -127.0 °C; for hexane – from -98.0 to -92.0 °C; for octane – from -60.0 to -54.0 °C. A comparison of the certified values of the developed reference materials for melting temperature with reference melting temperature values showed that the certified characteristics of the proposed reference materials agree within ± 0.2 °C; the differences are mainly due to the chemical purity of the substances.

As proof of the applicability of the secondary thermometry method, a set of reference materials for phase transition temperatures of the approved type OPG SO UNIIM has been released. As a result, testing laboratories will be able to establish and control the calibration dependence of thermal analysis measuring instruments, to validate measurement procedures (methods), and to monitor the accuracy of measurement results for the phase transition temperatures of metals, metal salts, metal oxides, polymer materials, and organic and inorganic substances.

Interlaboratory comparison tests, interlaboratory comparisons (ILC) in Russia are conducted in accordance with GOST ISO/IEC 170432013 “Interstate Standard. Conformity assessment General requirements for proficiency testing” (effective until April 10, 2026, after which it is superseded by GOST ISO/IEC 170432025 “Conformity assessment General requirements for the competence of proficiency testing providers”). Participation in ILC allows laboratories to monitor their performance, including comparing measurement results with those of other participants.

However, an analysis of ILC results obtained in 2021–2024 revealed hidden errors made by participants that led to unsatisfactory results. Thus, laboratories have not fully exploited the potential of ILC for monitoring their activities and identifying their own errors.

The objectives of the study presented in this article are to identify and analyse the main problems (errors) that can affect the reliability of measurement results and to draw laboratories’ attention to the possibilities offered by ILC for monitoring and improving their performance.

To this end, the results of ILC conducted by UNIIM – Affiliated Branch of the D. I. Mendeleyev Institute for Metrology were analysed. The study was based on ILC results for the objects “air environments”, “petroleum products”, and “food products”. During such ILC, participants obtained quantitative measurement results using equipment specified by the measurement procedure. The analysis described in this study did not cover qualitative and interpretative ILC programmes.

The analysis identified possible causes of unsatisfactory ILC results, provided examples and recommendations to help prevent unsatisfactory measurement results in the future.

The study established the main causes of errors: random errors, systematic errors, and errors related to incorrect descriptions of measurement procedures and/or calculation of measurement results in documents containing measurement procedures. The researchers concluded that with careful attention by laboratories to ILC results and regular participation in ILC, the proportion of unsatisfactory ILC results decreases significantly. Such attention leads to improved laboratory performance and, consequently, to increased reliability of measurement results.

The materials of the article are of an applied nature. The authors have demonstrated that analysis of each deviation in ILC results can improve the reliability of measurement results, as well as the effectiveness of this procedure in preparing laboratories for accreditation. The practical recommendations proposed for critical analysis of measurement results obtained during ILC are based on the extensive experience of the provider, whose staff are the authors of the article.

Verification, calibration and graduation of measuring instruments based on non-destructive methods for coating parameter inspection (in particular, X-ray fluorescence) require reference materials for coating thickness. These reference materials are specimens in the form of discs or rectangular parallelepipeds with metallic coatings deposited on them. The certified values of coating thickness for reference materials developed using X-ray fluorescence analysis are established indirectly – using the measured value of surface density and the density of the coating material, which until now in the Russian Federation and other countries has been a reference value. In practice, the density of the deposited coating material differs from the reference value, which leads to incorrect determination of coating thickness.

The aim of the study is to develop reference materials whose certified coating thickness characteristic will be established using the measured value of the coating material density. For this purpose – to determine the coating density – a physical and mathematical model was developed that implements the hydrostatic weighing method, based on the difference in volume between a sample with a coating and without a coating, and taking into account corrections for the density of the ambient air and the density of the working liquid. The experimental part was carried out on equipment from the State Primary Standard of the units of surface density and mass fraction of elements in coatings GET 168–2015.

As a result of the study, a measurement procedure for the density of coating materials was developed, tested and certified in the density range of coating materials (6–10) g/cm³ with an expanded uncertainty of measurements of the density of coating materials from 0.80% to 2.6%. Six types of reference materials of surface density and thickness of single-layer single-component coatings were developed and tested for approval in the coating thickness range (8–33) µm with an expanded uncertainty of coating thickness measurements from 1.5% to 2.9%

Using the developed and certified measurement method for the density of coating materials, metrological assurance of measurements of the thickness of single-layer coatings using the X-ray fluorescence method has been implemented. The field of application of reference materials of thickness and surface density of metallic single-layer single-component coatings is scientific research, mechanical engineering and instrument engineering.

In 2021, the Laboratory of Metrology of Magnetic Measurements and Non-Destructive Testing of UNIIM Affiliated Branch of the D. I. Mendeleyev Institute for Metrology developed and certified a 5[th] class mass unit standard. The standard is intended for metrological support of industrial mass measuring instruments belt weigher and continuous weigh feeders.

However, the relative error of the certified 5[th] class mass unit standard, equal to 0.3 %, allowed verification only of belt weigher and continuous weigh feeders having an error of 1 % or more. Meanwhile, a significant portion of belt weigher and continuous weigh feeders have an error limit of 0.5 %.

The aim of the work is to reduce the error of the method for transferring the mass unit to the 5[th] class standard from 0.3 % to 0.16 %, thereby allowing the use of certified standards for transferring the mass unit to belt weigher and continuous weigh feeders with an error of 0.5 %.

The research is based on the material and technical facilities and the mathematical model of mass unit transfer used in 2021 during the certification of the initial 5[th] class mass unit standard.

An analysis was carried out of the dominant influencing factors arising during the transfer of the mass unit from the 4[th] class standard to the 5[th] class standard, and a set of measures was adopted to minimize them. The mathematical model of mass unit transfer was refined to account for the influence of the unloaded conveyor belt proportionally to its position relative to the belt weigher. Software implementing this mathematical model was developed with an increased sampling rate and built-in analysis algorithms. A speed sensor with a measurement error reduced to 0.06 % was installed. Mechanical stabilization of the position and tension of the conveyor belt was adjusted.

As a result of eliminating the influencing factors and refining the mathematical model of mass unit transfer, it became possible to certify a 5[th] class mass unit standard having an expanded uncertainty (relative error) of 0.16 %. The practical significance of the work lies in the fact that it is now possible to provide accurate metrological support for high-tech weighing equipment under industrial operating conditions.