稀释倍数对氦中氩标准物质不确定度的影响

基于ISO 6142配制了多瓶He中Ar标准气体,并用氦离子化气相色谱（GC-PDHID）研究了稀释倍数对氦（He）中氩（Ar）标准气体的影响。结果表明,经过不同的稀释倍数所制备的浓度为50μmol/mol的标准气体有较好的一致性和小于0.05%的不确定度。稀释倍数越小,则稀释步骤所增加的不确定度越小,但稀释次数可能因此增加;稀释倍数越大,则稀释步骤导致的不确定度增加越大,但可降低稀释次数。在同样的稀释次数下,为每次稀释分配尽可能高的稀释倍数可减小标准气体量值的不确定度。

The Effect of Dilution Ratio on Uncertainty of Argon in Helium Gas Standards

The argon in helium gas standards were prepared based on ISO 6142. The 50 μmol /mol gas standards were prepared by different dilution methods and were then compared by a gas chromatography equipped with plasma ionization detectors（ GC-PDHID）. The results showed that the uncertainty of Ar in He gas standards was lower than 0. 05% after being diluted by 3 times when the dilution ratio was in the range of 1. 9 ~ 11. 1. Reducing the dilution ratio will decrease the uncertainty propagation but increase the dilution times for a given concentration. Thus,a proper dilution ratio should take both the uncertainty propagation and reducing the dilution times into consideration.