酸性滴定法测定水中COD_(Mn)的不确定度评定

Assessment of Uncertainty in Acid Titration Determination of COD_(Mn)

依据GB/T 5750.7—2006标准检测方法,结合本实验室检测工作经验、检测环境条件以及人员配置,按照检测步骤对CODMn测量不确定度的10个主要分量进行了逐一评定,并合成得到了本实验室测定CODMn的扩展不确定度:测定CODMn为2.63mg·L-1的水样时,ρ(O2)=0.20mg·L-1。评定结果表明:影响CODMn测量不确定度的主要分量来自空白实验的测量重复性和整个检测过程的测量重复性。这充分证明了要降低CODMn的测量不确定度不仅需要合格的实验条件和实验技能,还必须严格控制检测环境条件。

This study was based on GB/T 5750.7-2006 standard detection methods, and the work experience of laboratory, environmental conditions and staffing were taken into consideration. In accordance with the detection steps, ten main components of meas- uring uncertainty of CODMn were evaluated one by one, and the expanded uncertainty of CODMn of our laboratory were synthesized. When CODMn of water samples was 2. 63 mg · L-1, ρ（O2）=0.20 mg · L-1. The evaluation result shows that： repeatability tests of blank experiment and entire testing process were main sources of measurement uncer- tainty of CODMn. It was proved that to reduce the measurement uncertainty of CODMn need not only qualified experimental conditions and skills but also the strictly controlled environmental conditions.