甲烷中甲硫醇气体标准物质的研制

Preparation of methanethiol gas reference material in methane

以甲硫醇钠为原料,通过与稀硫酸反应制备甲硫醇。对甲硫醇和甲烷分别进行纯化,采用气相色谱-火焰光度检测器与气相色谱法氦离子放电检测器对纯化后的甲硫醇和甲烷进行纯度分析,甲硫醇纯度(摩尔分数)为99.75%,甲烷纯度(摩尔分数)为99.997%。通过称量法制备了甲烷中甲硫醇气体标准物质。采用气相色谱法火焰光度检测器对标准物质进行了均匀性检验、稳定性考察。研制的甲烷中甲硫醇标准物质标称浓度为100μmol/mol,F检验和回归曲线法实验结果表明,在压力0.5~10 MPa范围内,该标准物质具有良好的均匀性和稳定性,定值结果的相对扩展不确定度为2%(k=2),有效期为12个月。

Methyl mercaptan was prepared by the reaction of sodium methyl mercaptan with dilute sulfuric acid.After methyl mercaptan and methane were purified,the purity of methyl mercaptan and methane were analyzed by gas chromatography with flame photometric detector and gas chromatography with helium ion discharge detector.The purity of methyl mercaptan after purification was 99.75%,and the purity of methane was 99.997%.Methanethiol gas reference material in methane was prepared by weighing method.The homogeneity and stability of reference materials were tested by gas chromatography flame photometric detector.The nominal concentration of methyl mercaptan standard substance in the developed methane was 100μmol/mol.The experimental results of F test and regression curve method showed that the reference material had good homogeneity and stability in the pressure range of 0.5-10 MPa.The relative expanded uncertainty of the setting results was 2%(k=2),and the validity period was 12 months.