电感耦合等离子体质谱法和石墨炉原子吸收光谱法测定金银花中镉含量不确定度评估的比较

目的评定电感耦合等离子体质谱法(inductively coupled plasma mass spectrometry,ICP-MS)和石墨炉原子吸收光谱法(graphite furnace atomic absorption spectrometry, GFAAS)测定金银花中镉的不确定度。方法分别用ICP-MS法和GFAAS法测定金银花中镉含量,建立结果不确定度评估数学模型,分析与探讨测定过程中产生不确定度的来源。结果结果表明当镉的测定结果为0.217、0.226mg/kg时,其扩展不确定度分别为0.0096、0.0162 mg/kg, k=2。结论测定过程的不确定度主要来源于待测液浓度和斱法回收率。ICP-MS法引入的相对标准不确定度小于GFAAS法,能更合理地对样品中镉的不确定度进行合理评定。

Comparative study of uncertainty evaluation for the determination of cadmium content in Lonicerae Japonicae Flos by inductively coupled plasma-mass spectrometry and graphite furnace atomic absorption spectrometry

Objective To evaluate the uncertainty of determination of cadmium in Lonicerae Japonicae Flos by inductively coupled plasma-mass spectrometry (ICP-MS) and graphite furnace atomic absorption spectrometry (GFAAS). Methods The cadmium contents in Lonicerae Japonicae Flos were determined by ICP-MS and GFAAS, respectively, and the uncertainties were analyzed and discussed by the mathematical model of result uncertainty evaluation which was established. Results It resulted that the expanded uncertainties of these two methods were 0.0096 and 0.0162 mg/kg (k=2), respectively, when the determination results of cadmium were closed to 0.217 and 0.226 mg/kg. Conclusion The concentration of the solution to be measured and the recovery are major factors in calculating the uncertainty. The relative standard uncertainty introduced by ICP-MS method is less than that by GFAAS, which can reasonably evaluate the uncertainty of cadmium in samples.