石墨炉原子吸收光谱法测定猫须草中铅、镉的不确定度评定

Uncertainty evaluation of determination of lead and cadmium in orthosiphon stamineus by graphite furnace atomic absorption spectrometry

目的评定石墨炉原子吸收光谱法测定猫须草中铅、镉不确定度。方法依据GNAS-GL06:2006《化学分析中不确定度的评估指南》,综合测量结果数学模型和实验过程,分析不确定度来源,量化各不确定度分量,计算合成不确定度,最终得到铅、镉含量测定的扩展不确定度。结果在95%的置信区间下,猫须草中铅含量2.28×(1±0.149) mg/kg(k=2);镉含量0.0204×(1±0.0558) mg/kg(k=2)。评定结果表明,实验过程的不确定度主要来源于标准曲线拟合和加标回收率。结论通过建立测量数学模型,可对测定方法的不确定度进行合理的评定,为测定中药材、食材中重金属含量的不确定度分析提供参考。

Objective To evaluate the uncertainty of determination of lead and cadmium content in Orthosiphon stamineus by graphite furnace atomic absorption spectrometry. Methods According to GNAS-GL06：2006 Evaluation guide for uncertainty in chemical analysis, measurement results mathematical model and experimental process were synthesized, the sources of uncertainty were analyzed, the uncertainties of components were quantified, and the synthetic uncertainty was calculated. Finally, the extended uncertainties of lead and cadmium content determination were obtained. Results Under the 95% confidence interval, the lead content in Orthosiphon stamineus was 2.28×（1±0.149） mg/kg,（k=2）, and the content of cadmium was 0.0204×（1±0.0558） mg/kg,（k=2）. The evaluation results showed that the uncertainties of the experiment were mainly derived from curve fitting and adding standard recovery. Conclusion Through the establishment of the mathematical model of the measurement, the uncertainty of the measurement method can be reasonably assessed, which provides a reference for the uncertainty analysis of the determination of heavy metals in Chinese medicinal materials and food materials.