沉淀分离-电感耦合等离子体质谱法测定高温合金中痕量镉

镉对高温合金的力学性能和组织会产生有害影响,因此需控制和准确测定高温合金中镉的含量。采用电感耦合等离子体质谱法(ICP-MS)测定高温合金中镉时,样品中含量较高的钼对镉的测定产生干扰。采用盐酸-硝酸-氢氟酸溶解样品,加入乙酸铅与钼反应生成钼酸铅沉淀以实现钼与待测元素的分离,用铑为内标元素克服基体效应和仪器信号漂移,选择¹¹¹Cd为待测同位素,建立了ICP-MS测定高温合金中痕量镉的方法。采用扫描电子显微镜和微束分析能谱分别对沉淀静置前的悬浊液以及老化后得到的沉淀分析,优化了沉淀的条件。校准曲线的线性相关系数为0.999 8,检出限为0.070 μg/g,定量限为0.20 μg/g。选用中国科学院金属研究所自行冶炼的高温合金样品和高温合金标准物质为考察对象,采用实验方法对其中镉进行测定,测定结果分别与认定值或石墨炉原子吸收光谱法(GFAAS)测定值基本一致,实际样品测定结果的相对标准偏差(RSD,n=9)为0.46%～7.4%。

Determination of trace cadmium in superalloy by inductively coupled plasma mass spectrometry with precipitation separation

Cadmium has harmful effects on the mechanical properties and microstructure of superalloys,so the control and accurate determination of cadmium content in superalloys is important.During the determination of cadmium in superalloys by inductively coupled plasma mass spectrometry (ICP-MS), the high-content molybdenum in sample will cause interference.The sample was dissolved with hydrochloric acid-nitric acid-hydrofluoric acid. Lead acetate was added to react with molybdenum to form lead molybdate precipitate to realize the separation of molybdenum from testing elements.Rhodium was used as internal standard element to overcome the matrix effect and instrument signal drift.¹¹¹Cd was selected as the testing isotope.Finally,the determination method of trace cadmium in superalloy by ICP-MS was established.The suspension before precipitate standing and the precipitate after ageing were analyzed by scanning electron microscopy and energy dispersive spectrum,respectively,to optimize the precipitation conditions.The linear correlation coefficient of calibration curve was 0.999 8.The limit of detection and the limit of quantification was 0.070 μg/g and 0.20 μg/g,respectively.The superalloy samples and superalloy reference materials made by Institute of Metal Research (IMR) of Chinese Academy of Sciences (CAS) were for investigation.The content of cadmium was determined according to the experimental method.The found results were basically consistent with the certified values or those obtained by graphite furnace atomic absorption spectrometry (GFAAS).The relative standard deviations (RSD, n=9) of the determination results of actual samples were between 0.46% and 7.4%.