微波消解-自动电位滴定法测定铬矿石中三氧化二铬的不确定度评定

Uncertainty Evaluation in Determination of Chromium Oxide in Chrome Ores by Automatic Potentiometric Titrimetry with Microwave Digestion Sample Preparation

分析了微波溶样-自动电位滴定法测定铬矿石中主含量的检测过程,建立了测量过程分量的数学模型,讨论和比较了测量过程中各种不确定度因素,发现各不确定度因素中活塞滴定管滴定体积的不确定度贡献最大,其次是重复性对不确定度的贡献,而K2Cr2O7和Cr2O3的摩尔质量对最终不确定度结果的影响可以忽略不计。结果表明:采用硫酸亚铁铵溶液滴定方法,当样品中三氧化二铬的含量为40.17%时,其扩展不确定度U=0.40%。

The determination of chromium Oxide in chrome ores by automatic potentiometric titrimetry with microwave digestion sample preparation method was discussed.A mathematical model of measurement component was established to compare the uncertainty factors during measurement process.It was found that the uncertainty of titration volume of piston burette had maximal contribution,the uncertainty of measurement repeatability was in the second place,and the effect of K2Cr2O7 and Cr2O3 mol mass to the final uncertainty factors was minimum.It was found that,when ferrous ammonium sulfate titration method was used to determine Cr2O3 in chrome ores,an expanded uncertainty of 0.74% was recorded at Cr2O3concentration of 40.17%.