Metrological technical specification for purity assessment of organic pure substance certified reference materials in China

A metrological technical specification for the purity assessment of organic pure substance certified reference materials (CRMs) in China was formulated based on the practical experience from CRM developers, comments from experts, the “IUPAC Organic Purity Technical Report—Methods for the SI Value Assignment of the Purity of Organic Compounds”, and other references. After review by the national metrological technical committee for reference material and other experts in China, the specification was issued as JJF 1855–2020 in 2020. The specification describes the principles, requirements and practical guidelines for the purity assessment of organic pure substance CRMs, such as mass balance, quantitative nuclear magnetic resonance, differential scanning calorimetry, coulometry, titrimetry and external standard calibration. It also describes the combination for results and uncertainties for different methods. In which, the classification of mass balance method into three types and the combination approach of value and uncertainty, especially suitable for the purity assessment are firstly introduced. The introduction of the consideration during formulation for each important section in the specification is inspirational and instructive to developers of organic pure substance CRMs around the world.