钼同位素的MC-ICP-MS测定方法研究

本文报道了运用多接收器等离子体质谱进行Mo同位素组成测定的方法, 测定过程中的仪器质量歧视校正采用样品－标样交叉法。实验对Mo同位素测定过程中的谱峰干扰、基体效应、浓度效应、酸度效应和重现性等问题进行了详细研究。结果表明Zr的存在对Mo同位素测定不会产生影响; Sr不适合作为Mo同位素测定的元素内标; 当m(Ag)/m(Mo)≤1时, Ag的存在不会对Mo同位素测定产生影响; 当样品相对于标样的Mo浓度变化不大于50%时, Mo同位素分析不受浓度影响; 以HNO3为进样介质时, HNO3的浓度(0.1 mol/L~0.2 mol/L)对Mo同位素分析没有影响。CAGS-Mo相对于Alfa-Mo的δ100/95Mo、δ98/95Mo和δ97/95Mo分别为－0.34‰±0.10‰(2sd)、－0.22‰±0.05‰(2sd)和－0.13‰±0.08‰(2sd), 在95%的置信区间内, 该方法的外部精度不大于0.06‰/amu。

High-Precision Measurements of Mo Isotopes Using MC-ICP-MS

Techniques for high-precision measurements of Mo isotope ratios using MC-ICP-MS have been developed, which include assessment of isobaric inferences, matrix effects, concentration effects, acidity effects and long-term repeatability. The existence of Zr in the sample solution does not affect the accuracy of M, isotope ratio measurements. Sr is an unsuitable element spike of Mo. In the situation where m(Ag)/m(Mo)≤1, the existence of Ag in the sample solution does not affect the accuracy of Mo isotope ratio measurements. No effect was observed when the Mo concentration difference between the sample and the standard was not higher than 50% or the variation in acidity was from 0.1mol/L to 0.3mol/L. The external precision obtained using the method reported here is not less than 0.06‰/amu at the 95% confidence.