Creating Reference Standards for the Implementation of the State Verification Scheme for Water Content Measurement

The results of the development of methods for the transfer of units of water content in solid and liquid substances and materials are presented. Four types of comparison standards have been created for the transfer of units of water content, reproduced at the State Primary Standard of units of mass fraction, mass (molar) concentration of water in solid and liquid substances and GET 173–2017 materials. The procedures for the preparation of reference standards materials based on a mixture of organic solvents that are stable in water content and sodium molybdate dihydrate, which has chemically bound (crystallized) water, are described. The methods of reproducing the units of water content used in determining the characteristics of reference standards are presented: coulometric and volumetric Karl Fischer titration, air-heat drying and thermogravimetric analysis with mass spectrometric detection. The characteristics and standard uncertainties of the comparison standards, due to the characterization method, heterogeneity, long-term and short-term instabilities, are evaluated. The main changes adopted within the framework of the processing of the State verification scheme for means of measuring the water content in solid and liquid substances and materials are described.