杜马斯燃烧法测定肥料中总氮含量的测量不确定度评定

Evaluation of Uncertainty in Measurement of Total Nitrogen Content in Fertilizer by Du Masi Combustion Method

采用杜马斯燃烧法测定肥料中总氮含量,依据实验方法和《测量不确定度评定和表示》(JJF 1059.1—2012)的要求,建立不确定度数学模型,分析其来源,并计算各不确定度分量、合成不确定度及扩展不确定度。结果表明,杜马斯燃烧法测定肥料总氮含量的不确定度来源按照占各分量总和比例由大到小排序为仪器校准(66.84%)、标准物质(15.42%)、称量样品(9.66%)和测量重复性(8.05%);采用杜马斯燃烧法测定肥料总氮含量的扩展不确定度为0.38%(k=2)。

The Dumas combustion Methods was used to determine the total nitrogen content in fertilizer,and the mathematical model of uncertainty was established according to the experimental Methods and JJF 1059.1—2012,the sources of uncertainty were analyzed,and the components of uncertainty,synthetic uncertainty and extended uncertainty were calculated.The Results showed that the sources of uncertainty in the determination of total nitrogen content in fertilizers by the Dumas combustion Methodsare arranged in descending order according to the proportion of the sum of each component was as follows:instrument calibration(66.84%),standard material(15.42%),weighing sample(9.66%)and measurement repeatability(8.05%).The extended uncertainty of Dumas combustion Methods was 0.38%(k=2).