定量环法制备气体标准物质

定量环法制备气体标准物质

方正　周鑫　李志昂　邓凡锋　董了瑜　郑力文

中国测试技术研究院

摘　要　高精度气体标准物质是保证化学计量准确性的一项重要前提，目前的天然气气体标准物质制备步骤繁琐、费时，不确定度水平低，难以满足天然气成分量的高精度测定。为此，研发了定量环（Loop）法制备气体标准物质的方法，对其加入微量原料的不确定度、制备过程的不确定度进行了评定，与传统稀释法制备过程进行了对比分析，并采用气相色谱法对其重量法定值进行了验证。研究结果表明：①传统制备方法称量气瓶必须使用量程大、精度低的天平，多级稀释会重复地引入称量过程中的不确定度；

②定量环法制备混合气体标准物质，制备步骤可以一步完成，制备过程中引入的不确定度降低了一个数量级；③定量环法减少了制备的步骤以及原料的使用量，提高了混合气体标准物质的制备效率；④定量环法已成功用于天然气及硫化物混合气体标准物质的制备中，有望得到更加广泛的应用，使得气体标准物质的制备更加高效、定值更加准确；⑤采用气相色谱法对该方法制备得到的混合气体标准物质的标称值进行方法验证，结论认为：该方法具有很好的可行性及准确性。

关键词　气体标准物质　化学计量　多级稀释　定量环　高精度　称量　不确定度评定

DOI: 10.3787/j.issn.1000-0976.2018.09.015

Application of the loop method to the preparation of gas reference material Fang Zheng, Zhou Xin, Li Zhi'ang, Deng Fanfeng, Dong Liaoyu & Zheng Liwen

(National Institute of Measurement and Testing Technology, Chengdu, Sichuan 610021, China) NATUR. GAS IND. VOLUME 38, ISSUE 9, pp.114-120, 9/25/2018. (ISSN 1000-0976; In Chinese) Abstract: High-accuracy gas reference material is an important prerequisite to guaranteeing the accuracy of stoichiometry. At present, however, the existing procedures of preparing gas reference material are complicated and time-consuming with high degree of uncertain-ty, so it is difficult to realize the high-accuracy measurement of gas compositions. In this paper, a loop method of preparing the gas refer-ence material was developed. Then, its uncertainty degree on trace materials and preparation process was assessed and compared with the preparation process of the traditional dilution method. Finally, its weighing value was verified by means of a gas chromatography. And the following research results were obtained. First, the weighing cylinder of traditional preparation methods need a balance of wide range and low precision, so the uncertainty degree in the weighing process is introduced many times by multi-stage dilution. Second, when the loop method is adopted to prepare mixed gas reference material, the preparation can be completed in one step, so the uncertainty degree introduced in the preparation process is decreased by one order of magnitude. Third, by virtue of the loop method, the previously-used preparation procedures are simplified, the consumption of raw material is reduced and the preparation efficiency of mixed gas reference material is increased. Fourth, the loop method has been successfully applied to the preparation of gas reference material of natural gas and sulfide mixtures, and it is promising in more extensive application to realize efficient preparation and accurate valuing of gas refer-ence material. And fifth, a gas chromatography is used to verify the nominal value of mixed gas reference material prepared by the loop method. And it is indicated that the loop method is of strong feasibility and accuracy.

Keywords: Gas reference material; Stoichiometry; Multi-stage dilution; Loop; High-accuracy; Weighing; Uncertainty assessment

基金项目：国家重点研发计划资助项目“生产安全与防护领域急需计量标准及标准物质研究”（编号：2016YFF0201101）、国家科技支撑计划项目“环境气体微痕量有害成分量值溯源关键技术研究”(编号：2013BAK12B04)。

作者简介：方正，1963年生，研究员，硕士；主要从事标准物质制备方法及化学计量量值溯源体系方面的研究工作。地址：（610021）四川省成都市成华区玉双路10号。电话：（028）84403173。ORCID：0000-0002-1100-9022。E-mail：fz_nimtt@