Metrological support of phthalate content measurements: reference material for the composition of a solution of six priority phthalates in methanol

The article provides information on the development of a new reference material (RM) for the composition of a solution of six priority phthalates (dimethyl phthalate, diethyl phthalate, di(n-butyl) phthalate, benzyl butyl phthalate, bis(2-ethylhexyl) phthalate, di(n-octyl) phthalate) in methanol provided with metrological traceability to GET 208-2019 (GET 208). The procedure for the preparation and certification of RMs is shown, including the estimation of homogeneity and stability. Pure organic substances (phthalates) characterized on GET 208 were used as the starting material for the RM. The RM material was prepared by weight and volume-weight methods. The stability study of the RM was carried out by the isochronous procedure. The RM certified values are the mass fraction and mass concentration of individual phthalates in the solution. When calculating the uncertainty budget for RM certified values, contributions from the purity of the starting materials, RM preparation procedures, heterogeneity, and long-term instability were taken into account. The relative expanded uncertainty of the certified values does not exceed 2 %. As a result, a certified reference material (CRM) was developed and approvedfor the composition of a solution of ortho-phthalic acid esters (phthalates) in methanol GSO 11366-2019. The practical significance of the application of GSO 11366-2019 is to ensure the metrological traceability of RM to the corresponding SI units reproduced on GET 208. The developed CRM can be applied in resolving any measuring tasks and performing a full range of metrological works.

Procedure of matter identification of reference material for composition of azithromycin with use of spectral method

In new medicinal products development, as well as actualisation of assessment approaches of medicinal products in circulation, the development of quality control procedures remains one of the most important issues in standardisation. Besides, such development should include using reliable, accurate and sensitive physicochemical methods which determine the need development and implementation of reference materials. This paper discusses the development of reliable methods for identifying the structure of azithromycin, which will guarantee the purity of the reference material, as well as adequately and unambiguously choose a method of quantitative determination in accordance with the current requirements of regulatory acts, and according to the Pharmacopoeia of the Russian Federation of the XIV Edition.

Features of «Plants» cluster from the reference materials collection IGC SB RAS

Four multielement reference materials compile the «Plants» cluster in the developed by IGC SB RAS collection. These are part of terrestrial plants (birch leaf, pine needles, mown meadow grass) and the aquatic plant Elodea canadensis (roots, stems, leaves and flowers). Plants that are sensitive indicators of the state of the environment are collected from unpolluted territories of Eastern Siberia (near and on Lake Baikal). The paper discusses differences in methods of selection and preparation of the material. Such features of these reference materials as granulometric composition (shape, size, particle size distribution), homogeneity and minimum representative mass of the sample, stability ofpowders under conditions of natural aging were studied in accordance with Russian and international requirements with the use of modern devices and methods of chemical analysis. The elemental compositions of matrix plant samples were evaluated according to the method of interlaboratory certification and are represented by the contents of more than 60 elements, of which 23 to 41 are certified. The participation of 20 to 38 accredited Russian and foreign laboratories and the use of more than ten different methods of analysis ensured the traceability of the results. The comparison of the developed and Chinese certified matrix plant reference samples demonstrated their consistency. Based on the results of the discussion of the characteristic properties offour plant PM, they are recommended for performing chemical measurements during the validation of existing and development of new analytical methods, quality control and evaluation of the traceability of the results of determining a wide range of elements in plant materials, as well as professional testing of laboratories of geo-ecological, pharmaceutical and agricultural organisations.

The choice of materials for the production of new reference materials of liquid viscosity certified in the interval of allowed temperature values from -40 °C to -5 °C

The article presents the results of research aimed at the selection of materials for the production of new reference materials intendedfor verification, calibration, and testing for type approval of means of measuring the viscosity of liquids, as well as certification of methods for measuring the viscosity of liquid media at temperatures below 0 °C. The developed reference materials are certified in the interval of allowed temperature values from -40 °C to -5 °C. This allows providing a wide range of modern methods for measuring the viscosity of liquids such as glass capillary viscometers, rotational viscometers, rheometers, etc.

Luminescence measurements: reference materials for composition of sodium adenosine triphosphate aqueous solution

The authors evaluated the possibility of using the luminometry method which allows checking the level of sanitation and hygiene in industries and is one of the most effective methods of «rapid microbiology». Such key stages of development of reference material for sodium adenosine triphosphate with the certified values as analysis of similar reference materials, selection of source material of the reference material, conducting experimental studies, and establishing the metrological characteristics of reference material with traceability to state primary measurement standard were provided in the paper. Considering that the selective optical density at the characteristic wavelength is directly proportional to the concentration of the absorbing component (sodium adenosine triphosphate), the stability of R M was studied by spectrophotometry. The stability of the RM material to assess the uncertainty of the measurement results was carried out by the isochronous method. The result of the study is the possibility of ensuring the traceability of measurement results based on luminescence to primary measurement standard by sodium adenosine triphosphate concentration. In addition to the above, the authors selected the optimal value of that concentration and established metrological properties for GSO 11606-2020 R M for the composition of sodium adenosine triphosphate aqueous solution (mass concentration: from 0,09 to 0,11 g/dm3; extended uncertainty: 0,015 g/dm3). Usage of this CRM in performing tests, calibrations, and verification of measuring instruments allows providing the unbiased assessment of the measuring capabilities of luminescent measuring instruments, including in terms of determining the error of the measurements carried out.

Reference standards-copies of mass unit: calibration 2020 using vacuum comparator CCL 1007

The article discusses the calibration results of reference standards-copies according to the State Primary Standard of the Mass Unit using the new CCL 1007 vacuum comparator and buoyancy artifacts. The authors provided historical data on the calibrations of copies of the International Prototype of the Kilogram (IPK) starting from 1892, including the Russian prototype № 12. The instability of the prototype of the kilogram No. 12 corresponds to international values and is assessed at 5 · 10–11 kg per year. Changes in the mass of copies are assessed in relation to the mass of the IPK, but it is impossible to determine to what extent it has changed. This was the reason for the adoption of a new value of the kilogram. Following the adoption at the 26th meeting of the General Conference on Weights and Measures (CGPM) held in Paris in November 2018, Planck constant was numerically established with absolute accuracy, and total uncer tainty of 1 · 10–8 kg was assigned to the mass of the IPK. Thus, the authors set the aim to preserve the numerical value of the total uncertainty of the reference standards-copies by reducing the transfer error of the State Primary Standard by 10 times. The article presents the calibration results of six reference standards-copies in relation to prototype No. 12 with the primary data processing using the method of least squares, and the uncertainty budget is provided. The calibration results of the reference standards-copies confirmed the accuracy increase of the transfer unit by 10 times in the range from 6 · 10–9 kg to 6 · 10–10 kg by the use of a vacuum comparator graduated 0.1 μg and buoyancy and sorption artifacts in direct measurements of air density. This has made it possible to compensate for the additional uncertainty attributed to the IPK based on the determination of the Planck constant value and to ensure the mass calibration of all accuracy grades preserving the entire hierarchical system of transferring the mass unit in the country.

Plant-matrix reference materials as a tool for ensuring the uniformity of chemical measurements in geochemistry, ecology, agriculture and pharmacology

The population needs reliable information on the chemical composition of plants and products made from them in order to preserve the environment and its safety. With the increase in cross-border trade, there is a growing demand for traceable results of determining the content of chemical elements in plants and not only proteins, fats, carbohydrates, pesticides, moisture, vitamins, etc., which can affect the quality of human life. An urgent but difficult analytical task is to obtain reliable measurements of the elemental composition of agricultural and wild plants and various products made from them. Reference materials (RMs) are a widely recognized tool for ensuring the uniformity of chemical measurements. They are designed for certification (validation) of existing and new methods (techniques) of chemical analysis, certification studies in the development of reference materials, and professional testing of laboratories. The article lists the reputable manufacturers of plant RMs in which the content of chemical elements is certified. The ratio of certified, reference, and quality control samples of plant-matrix has been assessed. The classification of certified reference materials according to the type of plant material used for their food application is provided. The contribution of different countries to the development of plant CRMs is hown. The selection of plants for the development of new RMs is discussed from two points of view, namely food composition databases (AOAC INTERNATIONAL) and the ‘Reference Plant’ chemical fingerprinting (B. Markert). Based on the consolidation of studies devoted to the development and appliance of plant-matrix reference materials, a list of the most important requirements has been compiled for reference materials that ensure the reliability and comparability of the results of chemical analysis in the fields of biology, geochemistry, ecology, agriculture, medicine, and interdisciplinary research.