在线加标-电感耦合等离子体质谱法测量纯钼中痕量杂质元素

纯钼的纯度或杂质含量对材料性能有重要的影响，痕量杂质的准确测量是产品质量控制的关键。电感耦合等离子体质谱法(ICP-MS)由于具有高灵敏、多元素同时测量的优势，是测量痕量杂质的最有效方法之一；但在测量高浓度纯钼基体中的痕量杂质时，会产生较强的基体抑制效应，严重影响测量结果准确性。基体匹配法、标准加入法以及基于同位素丰度比值测量的同位素稀释质谱法(IDMS)可以有效地补偿复杂的基体效应，获得准确的测量结果；但步骤繁琐、分析效率低、分析成本高使其难以满足高通量的测量需求。本万工作集成了标准加入法的准确性及在线自动分析的高效性，基于标准加入法的原理，通过双路进样，将样品溶液与标准溶液(系列标准溶液依次自动进样)同时引入三通进行混合，然后经过雾化进入ICP-MS进行检测，从而建立了基于在线加标的ICP-MS法。该方法有效地补偿了高浓度试样的基体效应，通过样品-标准进样流量差异的校正，提高了测量结果的准确性，实现了纯钼中29种痕量杂质元素的快速准确测量，满足了纯钼中痕量杂质标准物质的准确定值要求。经考察，本工作建立的方法对29种元素的方法检出限(MDL)在0.004～0.90μg/g之间，标准加入法标准曲线的线性相关系数r基本大于0.999，除Ca、Zn由于沾污问题导致的测量准确性较差外(Ca、Zn相对偏差分别为32%、13%)，27种元素的测量相对偏差在−6.8%～5.1%之间。将Cr、K测量结果与IDMS法比较，进一步验证了该方法的可靠性。结果表明，两种方法测量结果偏差在1%以内，且具有相当的精密度(本方法对于Cr、K的RSD为1.8%～3.2%，IDMS法的RSD为0.9%～1.4%)，但本方法分析效率与分析成本具有明显的优势，经评估15min可完成29种元素的测量，分析效率比IDMS法可提高上百倍，能够满足高通量的样品测试需求。

Rapid Determination of Trace Impurity Elements in Pure Molybdenum by Inductively Coupled Plasma-Mass Spectrometry Based on the Online-Standard-Addition Method

BACKGROUNDMolybdenum (Mo) is widely used in aerospace, nuclear industry, integrated circuits, flat display and photovoltaic solar energy and other fields[2-4]. The purity or impurity content of high purity molybdenum has an important effect on material properties, so the accurate measurement of trace impurities is the key to quality control. In the China national standard “Molybdenum Powder” (GB/T 3461—2016), the limits of impurities such as Pb and Bi which are commonly in the range of 5 to 50mg/kg, are specified. Rapid and accurate analysis of trace or ultra-trace impurities is necessary with the development of high purity Mo requirements of high throughput analysis.　　The ICP-MS method has become the most powerful method for trace impurities analysis in high purity Mo, but the tedious and time-consuming matrix effect calibration strategies makes it a big challenge to achieve rapid and accurate analysis. ICP-MS has the advantages of high sensitivity, good accuracy and the possibility of simultaneous measurement of multiple elements, compared with AAS, ICP-OES, and GD-MS methods. However, the matrix effect is heavy in the analysis of high purity Mo, which seriously affects the accuracy of the measurement results. Matrix matching method, standard addition method and isotope dilution mass spectrometry (IDMS) based on isotope abundance ratio measurement can effectively compensate for the complex matrix effect, and accurate analytical results can be obtained, but the analysis processes are complicated, the efficiency is low, and the cost is high, making it difficult to meet the measurement requirements of high throughput.　　To meet the requirements of rapid analysis, on-line analysis based on flow injection[28] and tandem calibration[29] was used. The online matrix separation and pre-concentration process for flow injection not only eliminates the matrix effect and reduces the detection limits, but also improves the automation level, and achieves high throughput measurement[31-33]. Wang et al.[32] measured a variety of trace metal elements in seawater samples within 28.5min based on online ion exchange. An online calibration process through a new analytical methodology called tandem calibration could be achieved based on a dual sample introduction system with two nebulizers working in parallel[29] or a multiple-channel nebulizer[34], for which the special design of the nebulizer is necessary.