酸及其浓度对多接收器等离子体质谱法测定Cu和Zn同位素的影响

运用多接收器等离子体质谱法 (MC-ICP-MS)测定同位素时,必须进行仪器质量歧视校正,而酸浓度对仪器质量歧视的影响是过去被忽视的问题.本实验以Cu和Zn同位素分析为例,研究了在HNO3和HCl介质进样条件下酸浓度对仪器质量歧视的影响.结果表明:HNO3 的浓度对Cu和Zn同位素的仪器质量歧视有显著影响,但二者并不同步;HCl的浓度在0.05 mol/L ～ 0.3 mol/L范围内对Cu和Zn同位素的仪器质量歧视没有影响.这说明与HNO3相比,HCl是一种更好的进样介质.在0.1 mol/L HCl 介质条件下,65Cu/63Cu 和66Zn/64Zn比值测定的长期重现性 (外部误差)均为0.00008 (2sd),比在HNO3介质下的重现性有明显改善.

Effects of Acid and Concentration on Cu and Zn Isotope Measurements by Multicollector-Inductively Coupled Plasma Mass Spectrometry

The effects of acid and its concentration on instrumental mass discrimination are issue which has not been investigated so far,although adequate understanding of the factors affecting the mass discrimination is essential for mass bias correction during isotopic measurements using the MC-ICP-MS.The results show that the acidity of HNO3 has significant effects on instrumental mass discrimination for Cu and Zn isotopes,but with different degrees for the two elements.No effect has been observed when the measurements were performed using HCl medium to certain extend of concentration variation from 0.05-0.30 molL.Thus it is proposed that HCl is a better medium than NHO3 for sample introduction for Cu and Zn isotope measurements using MC-ICP-MS.The repeatabilities for both65Cu63Cu and66Zn64Zn measurements in 0.1 molL HCl solution are both 0.00008(2sd),which are better than those in HNO3.