低浓度氮中二氧化硫气体标准物质的制备

以二氧化硫纯度标准物质和高纯氮气为原料,采用与一级标准物质比较法制备了摩尔分数为10~100μmol/mol的氮中二氧化硫标准物质。用二氧化硫分析仪对配制的标准物质进行了机械混匀试验、压力均匀性和时间稳定性试验。结果表明,滚动30~80 min后该标准物质机械混匀良好;经F检验,在10~0.5 MPa范围内该标准物质量随压力变化无显著差异,具有较好的压力均匀性;在–20℃和40℃条件下保存7 d,其量值无显著变化,可满足运输环节量值稳定性要求;在常温下贮存11个月,量值无显著性变化,满足国家二级标准物质稳定性要求。采用与一级标准物质比较法定值,并对定值结果的不确定度进行了评定。研制的低浓度氮中二氧化硫气体标准物质的标准值分别为9.89,55.4,101.2μmol/mol(U_(rel)=2%,k=2),该标准物质满足国家二级标准物质的相关技术要求,可用于仪器校准、测量过程质量控制及分析方法的确认和评价。

Preparation of Reference Material of Sulfur Dioxide in Nitrogen

The reference materials of sulfur dioxide in nitrogen 10-100 μmol/mol were prepared using purity certified reference material of sulfur dioxide and high purity nitrogen by the method of comparing with primary certified reference material. The content of sulfur dioxide in nitrogen and the homogeneity and stability of the reference material were determined by sulfur dioxide analyzer. After the process of 30-80 min mechanical blending, the concentration of the reference material maintained stable. The results showed that the reference value exhibited good uniformity with the change of the pressure from 10 MPa to 0.5 MPa and good stability after being stored for 11 months at room temperature and after being stored for 7 days at -20℃and 40℃, respectively, which could satisfy the requirements of transport and long-term stability of reference material. The determined value was obtained by comparing with the primary certified reference material, and the uncertainty of the result was evaluated. The reference value of sulfur dioxide in nitrogen were 9.89, 55.4, 101.2 μmol/mol (Urel=2%, k=2), respectively. The reference materials meet the technical requirements of the national reference material, which can be used for calibration of instrument, quality control of measurement, and confirmation and evaluation of analysis method.