电导率标准物质国内现状及其量值核查

    Domestic Status Quo and Quantity Value Verification of Certified Reference Materials for Electrolytic Conductivity

    • 摘要: 电导率标准物质是保证电导率测量结果准确一致的关键。本文从标准物质的定值方法、适用范围等方面综述了国内现有电导率标准物质的现状,深入分析了现有标准物质的特点及其不足。针对我国现有电导率标准物质中有超过50%标准物质的定值采用比较测量方法的现状,采用电解质溶液电导率国家计量基准对这些标准物质进行了量值核查。量值核查结果表明:采用比较测量方法对标准物质的量值进行定值准确性差、质量堪忧(总体合格率58%,较低量值标准物质合格率20%),亟需加强标准物质复制过程中的市场监管;比较测量方法对标准物质进行定值时,几个重要技术环节值得重点关注,即所使用电导率仪的准确度等级、实验室二级水电导率的准确测定、质量称量时空气浮力的正确修正、溶液定容时的准确定容以及标准物质定值不确定度的科学合理评定。

       

      Abstract: The certified reference materials (CRMs) for electrolytic conductivity are crucial to ensuring accurate and consistent conductivity measurement results. In this paper, the current situation of existing conductivity CRMs in China is reviewed in terms of their characterization methods and scope of application, and the characteristics of existing CRMs and their shortcomings are analyzed in depth. In view of the current situation that more than 50% of the existing conductivity CRMs in China are characterized by comparative measurement methods, the primary standard for the conductivity of electrolyte solutions was used to verify the values of these CRMs. The results of the verification show that: the accuracy and quality of the comparative measurement method for the characterization of the CRMs are poor (overall pass rate of 58%, the rate of CRMs with lower characterization values is 20%), and there is an urgent need to strengthen the market regulation in the process of replication of the reference materials. When the comparative measurement method for the characterization of the CRMs is being applied, several important technical aspects deserve attention, namely, the accuracy level of the conductivity meter used, the accurate determination of the conductivity of type II water in the laboratory, the correction of the air buoyancy when weighing the mass, the accurate fixing of the solution volume, and the scientific and reasonable assessment of the uncertainty of the characterization of the CRMs.

       

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