离子交换-电感耦合等离子体质谱法测定锆锡合金中痕量杂质元素

Determination of Trace Impurity Elements in Zircaloy by Ion Exchange-Inductively Coupled Plasma Mass Spectroscopy

锆锡合金具有优异的核性能,被广泛应用于核工业领域,其中的杂质元素含量通常控制在很低水平。电感耦合等离子体质谱(ICP-MS)是一种可进行多元素同时分析的无机质谱技术,已普遍应用于冶金分析领域。ICP-MS具有图谱简单、灵敏度高等优点,但也不可避免地存在质谱干扰问题,需要用其他辅助手段予以解决。ICP-MS测定锆锡合金中Cd含量时其所有同位素均被Zr和Sn的多原子离子或同质异位素干扰,需要进行基体分离。建立了ICP-MS测定锆锡合金中Cd, Al, B, Mg等11种痕量杂质元素含量的方法,其中Cd, Mg等6种元素经微型阳离子交换柱分离富集后测定,同时采用干扰校正方程校正了113In对113Cd的潜在干扰;其他杂质元素离子不经分离直接采用内标法测定。在稀氢氟酸介质中, Cd^2+等杂质离子被吸附在阳离子交换柱上,而Zr则形成络阴离子不被吸附,杂质元素与基体元素Zr分离并获得富集。杂质离子以盐酸洗脱后用ICP-MS检测,消除了测定Cd时Zr基体对其产生的干扰。主要研究了Cd元素与Zr基体的分离条件,包括上柱酸度、淋洗酸度、洗脱酸度、进样浓度和流速,同时考察了其他杂质元素在经优化实验获得的分离条件下的行为。结果表明, Mg, Mn, Co, Cu, Pb 5种元素具有与Cd类似的分离富集行为,可以同时进行测定。最终获得的分离条件为:流速2 mL·min^-1,泵入2 mL浓度为50 mg·mL^-1的样品(上柱酸度为0.5%氢氟酸),用0.5%氢氟酸淋洗9 min,用10%盐酸洗脱4.5 min后测定。方法的分离周期约为15 min,各元素的检出限介于0.005 8~0.21μg·g^-1之间,回收率在85%~110%之间, RSD值小于5%。采用本方法测定了Zr-zirlo核级锆锡合金样品中11种杂质元素的含量,结果的精密度和准确度均满足相应产品标准的要求。

Zircaloy has been widely applied in the nuclear industry for its excellent nuclear properties,in which the impurity element content is usually controlled at a very low level. Inductively coupled plasma mass spectrometry(ICP-MS)is an inorganic mass spectrometry for the simultaneous analysis of multiple elements and has widely been used in the metallurgical analysis. ICP-MS has such advantages as simple spectrogram and high sensitivity,but inevitably there is mass spectrum interference problems,which need to be solved by other auxiliary means. Matrix separation is required for all isotopes are interfered by polyatomic ions or isobars of Zr and Sn when Cd in zircaloy was determined by ICP-MS. A method for the determination of 11 trace impurity elements including Al,B,Mg in zircaloy by ICP-MS was developed,among which 6 elements such as Cd and Mg were separated and enriched by micro cation exchange column. The potential interference of 113In on 113Cd was corrected by the interference correction equation. Other impurity elements ions were directly determined by internal standard method without separation. Impurity ions such as Cd^2+ in dilute hydrofluoric acid were adsorbed on the cation exchange column, while Zr forms a complex anion which was not adsorbed, thus impurity ions was separated from matrix elements and got enriched. The impurity ions were eluted with hydrochloric acid and detected by ICP-MS, thereby eliminating the interference of Zr on the determination of Cd. The experimental conditions for the separation of Cd and Zr were studied, including medium acidity, leaching acidity, elution acidity, sampling concentration and flow rate. The behavior of other impurity elements under the separation conditions obtained by an optimization experiment was also investigated. The results demonstrate that Mg, Mn, Co, Cu, Pb have similar behavior of separation and enrichment to Cd and can be determined simultaneously. The final separation conditions were as follows. 2 mL sample with concentration of 50 mg·mL^-1 was pumped with a flow rate of 2 mL·min^-1(medium acidity was 0.5% hydrofluoric acid), then leached with 0.5% hydrofluoric acid for 9 min, and finally eluted with 10% hydrochloric acid for 4.5 min. The separation period of the method is about 15 min, and detection limit were 0.005 8~0.21 μg·g^-1. The recoveries ranged from 85% to 110%, and RSD is less than 5% for each element. The 11 impurity elements in Zr-zirlo zircaloy sample of nuclear grade were analyzed by this method, and the precision and accuracy of results both meet the requirements of corresponding product standard.