电感耦合等离子体质谱法测定固体废物中镉的不确定度评定

Uncertainty evaluation of the determination of cadmium in solid wasteby inductively coupled plasma mass spectrometry

建立电感耦合等离子体质谱法测定固体废物中镉含量的不确定度的评定方法。通过建立数学模型,分别对样品称量、样品溶液定容体积、系列标准工作溶液的配制、标准曲线拟合、测量重复性等影响不确定度的分量进行分析,计算合成不确定度以及扩展不确定度。固体废物中镉质量分数为0.421 mg/kg时,其扩展不确定度为0.0808 mg/kg(k=2,置信概率为95%)。标准曲线拟合是影响电感耦合等离子体质谱法测量固体废物中镉含量不确定度的最主要来源,其次为系列标准工作溶液的配制,而样品称量、样品溶液定容体积、测量重复性等分量的影响可忽略不计。

An uncertainty evaluation method for the determination of cadmium in solid waste by inductively coupled plasma mass spectrometry was established.By establishing a mathematical model,the factors affecting the uncertainty such as sample weighing,sample constant volume,standard curve preparation,calibration curve fitting and measurement reproducibility were analyzed.The results showed that the extended uncertainty of measurement was 0.0808 mg/kg(k=2,95% confidence probability)when the cadmium content in solid waste was 0.421 mg/kg.The results show that the calibration curve fitting was the main source affecting the uncertainty of cadmium content in solid waste measured by ICP�MS,followed by the preparation of standard curve,and the influence of sample weighing,sample constant volume,measurement reproducibility on the uncertainty of the method could be ignored basically.