富硒酵母中硒含量测定的不确定度评定

Evaluation of uncertainty in determination of selenium content in selenium-rich yeast

研究了影响富硒酵母经硝酸微波消解后通过电感耦合等离子体质谱仪测定的总硒含量的不确定度来源,并对其进行定量计算和比较分析。确定了影响总硒结果的相对标准不确定度以及扩展不确定度。结果表明:微波消解-电感耦合等离子体质谱法测定富硒酵母中硒的不确定度来源主要是三个方面,即标准曲线系列溶液的配制及标准曲线的线性拟合、样品硝酸微波消解前处理和仪器测定重复性,其相对标准不确定度分别为0.01175、0.01001、0.009488。当称样量为0.2073 g时,硒含量为2130 mg/kg,k=2(95%置信度),扩展不确定度为80 mg/kg,测量结果可表示为(2130±80)mg/kg。

The sources of uncertainty affecting the determination of total selenium content in selenium-enriched yeast by inductively coupled plasma mass spectrometry after microwave digestion with nitric acid were studied,and quantitative calculation and comparative analysis were carried out. The relative standard uncertainty and expanded uncertainty affecting the results of total selenium were determined. The results showed that the uncertainty sources of selenium in selenium-enriched yeast by microwave digestion-inductively coupled plasma mass spectrometry were mainly three aspects,namely,the preparation of standard curve series solution and the linear fitting of standard curve,the pretreatment of sample nitric acid microwave digestion and the repeatability of instrument determination.The relative standard uncertainty was 0.01175,0.01001 and 0.009488,respectively. When the sample weight was 0.2073 g,selenium content was 2130 mg/kg,k=2(95% confidence),and the expanded uncertainty was 80 mg/kg.The measurement results could be expressed as(2130 ±80)mg/kg.