石墨炉原子吸收光谱法测定矿泉水中总铬的不确定度分析

目的分析石墨炉原子吸收光谱法测定矿泉水中总铬的测量不确定度。方法应用测量不确定度评定理论,结合试验方法,建立数学模型,确定和计算测定过程各不确定度分量,分析石墨炉原子吸收光谱法测定矿泉水中总铬的测量不确定度。结果矿泉水中总铬含量为3.87μg/L,取包含因子k=2,其扩展不确定度为0.16μg/L,最终报告矿泉水中的总铬含量为（3.87±0.16）μg/L;同时对影响测定结果的不确定度的各部分因素进行了量化,由标准物质引入的相对不确定度分量urel（标准）=1.1%;由标准曲线引入的相对不确定度分量urel（拟合）=1.3%,由重复测定引入的不确定度分量urel（重复）=0.93%,由回收率引入的不确定度分量urel（Rec）=0.89%。结论影响测量结果的不确定度主要因素是标准曲线拟合引入的误差,标准物质及其稀释过程引入的不确定度次之,其他因素如环境条件、重复测定、回收率等对测量结果的不确定度影响较小。

Uncertainty analysis of detecting total chromium in mineral water by GFAAS

Objective An analysis of uncertainty in measurement of detecting total chromium in mineral water by Graphite Furnace Atomic Absorption Spectrometry（GFAAS）.Methods According to the theory of assessment on uncertainty,by establishing mathematical model,the factors causing the uncertainty of the detection of total chromium in mineral water by GFAAS were determined and calculated.Results The content of total chromium in mineral water was 3.87 μg/L,and expanded uncertainty was 0.16 μg/L（k=2）.The relative uncertainties of standards and curve were 1.1% and 1.3%,respectively.Besides,the relative uncertainties of replicate analysis and recovery were 0.93% and 0.89%,respectively.Conclusion The major factor influence the determination of total chromium in mineral water was the error introduced by standard curve fitting.The minor factor was dilution process of standards,and the others were the minimum factors.