红外吸收法测定土壤中硫含量结果的不确定度评定

为评定红外吸收法测定土壤中硫含量测定结果的不确定度，分析了测定过程中标准物质、称量、重复测量、仪器示值、助熔剂及瓷坩埚等来源所引入的不确定度，建立数学模型并计算出各标准不确定度分量，评定出合成标准不确定度为0．00073％，扩展不确定度为0．0015%．确定影响测量不确定度的主要来源是重复性测定及标准物质选用，而仪器示值引入的不确定度可忽略不计，天平称量和由助熔剂及瓷坩埚引入的空白需要注意控制，从而衡量出该分析方法的可靠程度．

Assessment of Sulfur Uncertainty the Soil by High Frequency Infrared Absorption Spectrometer

An assessment was carried out to determine the sulfur in soil by high frequency infrared absorption spectrometer,and the sources of uncertainty in this analytic method was analyzed such as standard materials,weighing,duplicate test,instrument showed value,fluxing agent and porcelain crucible etc.The mathematical model was established and the standard uncertainty components were calculated.The results showed that combined standard uncertainty was 0.00073% and extend standard uncertainty was 0.0015%.The sources of uncertainty came mainly from duplicate test and selected standard materials,whereas the uncertainty from instrument showed value could be ignored.It was necessary to control weighing,fluxing agent and porcelain crucible during the measurement.