复混肥料中总氮含量测定的不确定度评定

Evaluation of Uncertainty in Determination of Total Nitrogen Content in Compound Fertilizer

根据国家标准《复混肥料中总氮含量的测定蒸馏后滴定法》(GB/T 8572—2010),采用蒸馏后滴定法测定仅含铵态氮复混肥料中的铵态氮含量,并对测定过程中的不确定度来源进行了分析,主要为样品的测量重复性和滴定用标准溶液的体积。按《测量不确定度评定与表示》(JJF 1059.1—2012)的规定进行不确定度计算,复混肥料中铵态氮的合成标准不确定度为0.050%,扩展不确定度为0.10%,测定结果为15.42%±0.10%(k=2)。

According to the national standard"Determination of total nitrogen content for compound fertilizers titrimetric method after distillation"(GB/T 8572—2010),the titrimetric method after distillation is used to determine the ammonium nitrogen content in compound fertilizer containing only ammonium nitrogen.The sources of uncertainty in the determination process are analyzed,mainly the measurement repeatability of the sample and the volume of the standard solution for titration.The uncertainty is calculated according to the provisions of"Evaluation and expression of uncertainty in measurement"(JJF 1059.1—2012),the synthetic standard uncertainty of ammonium nitrogen in compound fertilizer is 0.050%,the expanded uncertainty is 0.10%and the determination result is 15.42%±0.10%(k=2).