气相色谱法测定汽油中苯含量不确定度的评定

通过分析气相色谱法测定汽油中苯含量的操作流程对汽油中的苯含量测量结果的不确定度进行了评定,不确定度主要来源于相对定量校正因子、样品中添加内标物丁酮的体积、样品的体积、样品中苯与内标物丁酮面积的平均值之比、标准物质苯的纯度等参数引入的不确定度。其中相对校正因子引入的不确定度最大。当汽油样品中苯的体积分数为0.57%时,苯含量的扩展不确定度为0.02%(k=2)。

EVALUATION OF THE UNCERTAINTY OF DETERMINATION OF BENZENE IN GASOLINE BY GAS CHROMATOGRAPHY

With the analysis of the operation process,the uncertainty of determination of benzene in gasoline by gas chromatography was evaluated.The main sources of the uncertainty were the uncertainties of measurement of relative correction factor,volume of the sample,volume of the internal standard injected in sample,the ration of peak areas of benzene and 2-butanone in sample,the purity of benzene as the standard reference.Chief among them was the effect of relative correction factor.The expanded uncertainty was 0.02%,when the content of benzene in gasoline sample was 0.57%.