测定水样中化学需氧量的不确定度

Evaluation on the Uncertainty of COD Determination in Aqueous Medium

对化学需氧量测定的不确定度进行合理评定,应充分考虑测定过程中的不确定度来源。建立了重铬酸钾法测定水样中化学需氧量不确定度的数学模型,对组成化学需氧量的各个因子的不确定度分量进行了详尽的分析和计算,得出了本次样品CODCr的测定结果为72.2mg/L,扩展不确定度为3.8mg/L。

The sources of uncertainty during measuring process should be fully considered when evaluating the uncertainty of COD determination in aqueous medium.We established a mathematical model of the uncertainty of COD determination by potassium dichromate(K2Cr2O7)method,and then the uncertainty of COD determination were analyzed and calculated in detail for all factors which compose COD.The results showed the COD of the water sample was 72.2 mg/L,and the expanded uncertainty was 3.8 mg/L.