脉冲-辉光放电质谱法测量稀土合金中的关键元素

摘要

Pulsed glow discharge mass spectrometric(Pulsed-GDMS) method for the measurement of 7 kinds of key elements(Mg,Fe,Cu,La,Ce,Pr and Nd) in rare earth alloys was established. The influence factors of measurement repeatability, such as pulse time, sample homogeneity, anode cap, flow tube, corn, and sample tablet density were systematically studied. The results showed that,for elements with mass fraction of more than mg/g, the parts (anode cap, flow tube and corn) had the largest influence on measurement repeatability. When the new graphitic parts were used and no parts were changed during the whole measurement,the relative standard deviation (RSD) was less than 3%. However, the RSD were 2%-11%and 3%-21% when the new graphitic parts and the reusable parts were used and changed,respectively. The second influence factor of measurement repeatability was the tablet density. The results showed that,the lower the density,the worse the measurement repeatability, and for the dense tablet, the RSD was less than 3%. Key elements in 1# rare earth alloy were measured by high resolution inductively coupled plasma-mass spectrometry (HR-ICP-MS), and the analytical results were used as reference values for the calibration of Pulsed-GDMS. The relative sensitivity factors (RSF) were obtained, and the key elements in 2# rare earth alloy were measured by Pulsed-GDMS after calibration. The analytical results of key elements in 2#sample by Pulsed-GDMS and HR-ICP-MS were compared, and the results showed that for the dense sample, the analytical results showed good agreement. Under the optimal conditions, the expanded uncertainty of measurement by Pulsed-GDMS reduced to 3%-10%.%建立了脉冲-辉光放电质谱(Pulsed-GDMS)测定稀土合金中7种关键元素Mg、Fe、Cu、La、Ce、Pr、Nd的分析方法.系统考察了脉冲时间、样品均匀性、质谱仪配件(阳极帽、导流管、样品锥)、压片致密性对测量重复性的影响.对于含量在mg/g量级以上的元素,影响重复性(RSD)的最大因素是质谱仪配件的更换,不更换配件RSD <3%,更换新配件RSD为2% ~11%,更换重复使用的旧配件RSD为3% ~21%;其次是粉末样品压片的致密性,致密样品的测量结果RSD <3%,致密性越低,测量重复性越差.采用高分辨电感耦合等离子体质谱(HR-ICP-MS)对1#稀土合金样品中的元素进行测量,以测量值为参考值对Pulsed-GDMS的测量结果进行校正,获得各元素的相对灵敏度因子,用校正后的Pulsed-GDMS对2#稀土合金样品进行测定.结果表明,对于致密样品(2#-A)的Pulsed-GDMS分析结果与HR-ICP-MS分析结果一致.在优化的条件下,实际样品测量结果的扩展不确定度可降低至3% ~10%.