原子吸收石墨炉法测定圆白菜中铬含量结果的不确定度评定

Evaluation of uncertainty for determination of Cr content in cabbage by graphite furnace atomic absorption spectrometry

为评定不确定度分量对石墨炉原子吸收光谱法测定圆白菜中铬含量的影响程度,依据《测量不确定度评定与表示》(JJF 1059-1999),分析了铬含量测定过程中的不确定度来源,通过建立数学模型量化不确定度分量,计算合成不确定度及扩展不确定度。结果表明,测得的圆白菜试样中的铬含量为(1.50±0.24)mg/kg(k=2),测定过程的不确定度来源主要有测量重复性、试样中的铬浓度、试剂空白液中的铬浓度、试样质量、试样定容体积等。该方法能如实反映测量的置信度和准确性,可为日常实际检验工作提供参考。

In order to evaluate the uncertainty of determination of Cr content in cabbage samples by graphite furnace atomic absorption spectrometry,according to the JJF 1059-1999 Chinese Regulation on the Valuation and Expression of Uncertainty in Measurement,the sources of uncertainty in determination of Cr content in cabbage samples are analyzed.Furthermore,the combined uncertainties and expanded uncertainties are calculated based on the established mathematic models of evaluation uncertainty.The result shows that the Cr content in cabbage samples in this study is（1.50±0.24）mg/kg（k=2）,and the main sources of uncertainty in the determination are as follows：repeatability of measurement,Cr content in cabbage samples,the quality of the samples,Cr content in reagent blank and the constant volume.This method accurately reflects the confidence and accuracy of the measurement,and provides reference for the daily actual inspection work.