硫酸亚铁铵滴定法测定锰含量的不确定度评估

Evaluation of Uncertainty in Determination of Manganese Content by Ammonium Fer⁃rous Sulfate Titration Method

为判断锰砂滤料中锰含量测定结果的准确度,对GB/T 1506—2016 《锰矿石锰含量的测定电位滴定法和硫酸亚铁铵滴定法》标准中规定的硫酸亚铁铵滴定法检测锰砂滤料中锰含量的结果进行不确定评估。按照标准中规定的检测方法,建立了测量数学模型,确定会引入不确定度的五个分量。经过评估,五个分量对不确定度的影响程度按大小排序为:样品湿存水量测定>标准溶液标定>滴定样品消耗硫酸亚铁铵标准溶液体积>标准溶液配制>样品称量;在锰砂滤料样品的检测过程中,湿存水量测定的不确定度占比最大,占比为92.2%,可以通过增加检测锰砂滤料样品湿存水量的的次数来减小湿存水量对不确定度的影响。

In order to judge the accuracy of the results of the determination of manganese content in manganese sand filter material,the results of the determination of manganese content in manganese sand filter material by ammonium ferrous sulfate titration method specified in the standard of GB/T 1506-2016 Determination of manganese content in manganese ores by potentiometric titration and ammonium fer-rous sulfate titration method are evaluated with uncertainty.According to the measurement method specified in the standard,a measurement mathematical model is established,and the five components that will introduce uncertainty are determined.After evaluation,the influence degree of the five com-ponents on uncertainty is ranked in order of magnitude:sample hygroscopic moisture content measure-ment>standard solution calibration>standard solution volume of ammonium ferrous sulfate consumed by titration sample>standard solution preparation>sample weighing.In the detection process of man-ganese sand filter material samples,the uncertainty ratio of hygroscopic moisture content measurement is the largest,accounting for 92.2%.The influence of hygroscopic moisture content on uncertainty can be reduced by increasing the number of detection times of hygroscopic moisture content of manganese sand filter material samples.