使用气相色谱／质谱测定汽油中元素硫含量的不确定度评定

使用气相色谱／质谱测定汽油中元素硫含量，采用样品直接进样和外标法定量，该分析方法简单、快速、灵敏，且无干扰。根据不确定度的传播规律，对所用标准曲线、有证标准样品、称重、合格的玻璃器皿、测量重复性等不确定度来源进行分析评定，其中由标准曲线上求元素硫含量时所产生的不确定度分量最大，其次是测量重复性，这两项是该法测定结果不确定度的重要来源，标准溶液浓度所产生的不确定度分量较小。置信度为95％时，高、低浓度样品元素硫含量的扩展相对不确定度分别为6．4％和4．2％。

An Evaluation on the Uncertainty of Determining Elemental Sulfur Content in Gasoline by GC/MS

While the elemental sulfur content in gasoline is determined by Gas Chromatography/ Mass Spectrometry (GC/MS), the sample oil is directly injected and quantified by external standard method. This analysis method is simple, fast, sensitive and interference-free. According to the transmission rules of uncertainty, the source of uncertainty were analyzed and evaluated, which include the used standard curves, the certificated standard, the weighing, the eligible glass vessels and the determination repeatability. The largest uncertainty was caused by the elemental sulfur content calculation based on the standard curve. The next was brought about by the determination repeatability. These two items are the important uncertainty sources of this determining method. At the same time, the relative small uncertainty was due to the standard solution concentration. When the confidence level was 95%, the expanded relative uncertainty was 6.4% and 4.2% respectively for the elemental sulfur content sample with high and low solution concentration.