Reference materials, which have sufficiently homogeneous and stable properties, act as a precise referee and are widely used in various activities such as calibration of measurement systems, evaluation of measurement methods and proficiency testing, and quality control of measurement results. They are a bridge to establish comparable results and mutual trust, and are an important measurement tool for creating and controlling quality. The development of reference materials is like a dancer, which is inseparable from the stage of technical standards and specification systems, and also depends on the tacit cooperation of various preparation and valuation technologies.
For certified reference materials, the standardization, traceability and accuracy of their development are like every movement of a dancer, which has higher requirements. They follow the metrological traceability chain to build a measurement program, measurement system and reference material system that meet the requirements of different metrological traceability levels, which ensures that the measurement results are comparable due to traceability, equivalent due to comparability, and mutual recognition due to equivalence.
In this process, the national metrology institutes play an important role, like a director, carefully build a traceability system for the quality value of standard materials, and promote the mutual recognition of measurement results across the country. They are like the soul of the dancer, giving life and motivation to the reference material system, enabling it to dance in the field of metrology.
, basic concepts
The development of various detection technologies has brought about a wide variety of reference material needs, and has also promoted changes in their basic conceptual systems. A comparison of the concepts of Reference Materials and Certified Reference Materials in the early and current versions of ISO IEC Guideline 30 and ISO IEC Guideline 99 (VIM) [1,2] reflects a further expansion of the conceptual scope.
With the market-oriented development of reference materials and the promotion and implementation of self-declaration and voluntary accreditation systems, the identification method of issuing certificates of certified reference materials by authoritative institutions in VIM has been broken.
2. Analysis of development status.
With the rising demand and the continuous expansion of application fields, the number and variety of global reference materials have developed rapidly in recent years. Its R&D and production are divided into two camps, one is the fast-growing commercial reference material research institute;The other type is represented by the National Institute of Metrology, international organizations, etc., and carry out the research and development of certified reference materials from the perspectives of strategic and regulatory needs, the construction of the traceability system and public welfare resources.
Key R&D directions and new varieties of metrology institutes of various countries.
National metrology institutes are committed to the development of benchmark value technology that can be traced to SI. For example, NIST has developed an ultra-pure and comprehensively characterized benzoic acid reference material for quantitative nuclear magnetic resonance, clearly identified the chemical structure, determined the isotopic composition and molecular weight, and measured the amount of the substance by QNMR and Coulometric reference measurement methods respectively, and verified the purity by mass balance method, which provides the highest level of traceability basis for the quantitative nuclear magnetic resonance purity measurement of various organic compounds.
3. Analysis of domestic development status
In terms of China's national reference materials, according to the statistics of the national reference material resource sharing platform, the total number of approved materials by the end of 2021 has exceeded 15,000, including 3,000 first-class reference materials and 12,000 second-level reference materials. From the perspective of the first-class reference materials with relatively non-repetitive varieties and characteristic value types that can represent the highest level of development in China, the number of varieties in the fields of geology and minerals, food, clinical, environmental, and physicochemical properties has increased the most.
System of international standards and guidelines
For many years, it was recognized that meeting the demand for reference materials was as important as global consistency of quality requirements. Based on this, the International Organization for Standardization Reference Materials Committee (ISO Remco) was established in 1975 and has successively issued a series of international guidelines on the definition of reference material terms, certificates and other accompanying documents and labels, selection and use, valuation and uniformity and stability assessment, and internal preparation of quality control substances, and the current effective versions are ISO Guidelines 30:2015, Guidelines 31:2015, Guidelines 33:2015, Guidelines 35:2017, and Guidelines 80:2014.
Domestic standards and norms system
China's metrology department and standardization department have carried out the transformation of ISO-related international standards and guidelines, and established a system of relevant technical standards or specifications for reference materials and standard samples according to their respective needs, which are GB T 15000 series national standards and JJF series national metrology technical specifications.
In order to address the challenges and needs of the world's major metrology areas, the International Advisory Committee on Material Quality (CCQM) has published a strategy document 2021-2030, which identifies 9 metrology challenges and needs. On the domestic side, the "Metrology Development Plan (2021-2035)" issued by ** puts forward the requirements for establishing and improving the reference material system, including national reference materials, national reference materials and working reference materials. At the same time, the plan also requires the implementation of the reference material capacity improvement project, and accelerates the development and application of reference materials in key areas such as life sciences, biomedicine, environmental monitoring, food safety, natural resources, and criminal justice. These requirements are to meet the challenges and needs of major global measurement fields and promote the development and application of domestic metrology technology.