称量法配制二氧化硫标准物质的不确定度

Evaluation of Uncertainty of Gas Reference Material of Sulfur Dioxide by Weighing Method

采取国际通用的称量法设计配制氮气中二氧化硫气体标准物质的方法,包括制备、充装、定值、稀释等。用气相色谱法进行浓度验证、减压、均匀性、稳定性等实验,保障了所制备的标准气体量值准确、稳定可靠,满足了对计量器具仪器检定和校准的使用要求,对二氧化硫的监控更加有效。经试验综合可知,摩尔分数为409×10-6的氮气中二氧化硫气体标准物质,量值准确,示值误差不超过±5%,稳定性不超过1%,不确定度Urel=2.2%(k=2)。有效使用期不少于6个月,达到国家二级标准物质要求。不仅浓度范围达到使用要求,还节约了成本。

Preparation methods of gas reference material of sulfur dioxide in nitrogen is designed adopting weighing method which is international general,including production,filling,valuing,dilution,homogeneity and stability examination,uncertainty evaluation,etc. To ensure gas reference material has accurate quantity,and is also stable and reliable,gas chromatography method is used in concentration verify,decompression,uniformity,stability test. The requirement of effective verification and calibration of measuring instruments is satisfied,and the monitoring of sulfur dioxide is more effective. The comprehensive experiment shows that gas reference material of sulfur dioxide in nitrogen whose concentration is 409μmol/mol has accurate value. The indication error is less than ± 5%,the stability is less than 1%,and the uncertainty Urel=2. 2%（ k = 2）. The effective use period shall be more than 6 months,meeting the requirements of the national second-level reference material. The concentration range is not only up to the requirement,but also saves cost.