重铬酸盐法测定水中化学需氧量不确定度评估

Uncertainty Evaluation of Determination of Chemical Oxygen Demand in Water by Dichromate Method

不确定度的评定是测量结果的重要部分,反映了测量结果的可靠性以及检测过程中各项不确定度来源对测量结果的影响程度。实验室对重铬酸盐法测定水中化学需氧量的不确定度进行评定。分析发现硫酸亚铁铵的浓度对结果的影响最大。对有证质控样品[证书编号:B2006152,浓度为(274±14)mg/L]重复测定,测试结果为(276±4)mg/L(k=2),测试结果在证书给定范围内。

The evaluation of uncertainty is an important part of the measurement results,which reflects the reliability of the measurement results and the influence of various sources of uncertainty on the measurement results in the detection process.The uncertainty of determination of chemical oxygen demand in water by dichromate method was evaluated in the laboratory.It was found that the concentration of ammonium ferrous sulfate had the greatest influence on the results.Repeating the determination for the certified quality control sample[Certificate No.B2006152,concentration(274±14)mg/L],the test result was(276±4)mg/L(k=2),and the test result was within the given range of the certificate.