火焰原子吸收光谱法测定配合饲料中铜、铁和锰含量的不确定度评定

Uncertainty Evaluation of Copper,Iron and Manganese in Feed by Flame Atomic Absorption Spectrometry

研究旨在建立火焰原子吸收光谱法测定配合饲料中铜、铁和锰含量的不确定度评定方法,真实反映测量的置信度和准确性。首先分析测定过程中的不确定度来源,对不确定度分量进行量化,然后通过数学模型计算出饲料中铜、铁和锰含量,合成扩展不确定度。结果显示:饲料中铜、铁和锰的含量分别为(11±2)、(214±10)、(92±4)mg/kg,不确定度为扩展不确定度,包含因子为2,对应的置信水平是95%。本研究发现样品消解、样品溶液浓度测定和含量重复性测量是影响饲料中铜、铁、锰含量测量中不确定度的主要因素,应特别关注样品的前处理过程、标准工作液的配制,并使待测样品的浓度落在曲线的中间位置,以提高检测准确性。

The study was to establish a method for uncertainty evaluation of Cu,Fe and Mn content in feed by flame atomic absorption spectrometry,and to reflect the confidence and accuracy of the measurement.The sources of uncertainty in the determination process were analyzed,and the uncertainty components were quantified.Then the contents of copper,iron and manganese in the feed were calculated by mathematical model to synthesize the extended uncertainty.The results showed that the contents of Cu,Fe and Mn in diets were(11±2)mg/kg,(214±10)mg/kg and(92±4)mg/kg,respectively.The uncertainty was an expanded uncertainty with a factor of 2 and a confidence level of 95%.Sample digestion,sample solution concentration determination and content repeatability measurement are the main factors affecting the measurement uncertainty of copper,iron and manganese in feed.Special attention should be paid to the sample pretreatment process and the preparation of standard working solution.To improve the detection accuracy,the concentration of the sample should be adjusted to the middle of the standard curve.