激光剥蚀-电感耦合等离子体质谱准确测定锆石中钛的含量

摘要

外标物质及内标元素的选择是激光剥蚀-电感耦合等离子体质谱(LA-ICP-MS)准确测定元素含量的关键因素之一.文章选用玻璃标准参考物质NIST 610、GSE-1G、BHVO-2G、BCR-2G、ATHO-G、KL2-G和T1-G作为外标,Si或Zr作为内标,对锆石M257中的Ti进行LA-ICP-MS微区原位测定.结果显示,选择Si或Zr作内标,采用BCR-2G、ATHO-G、KL2-G和T1-G作外标时,Ti含量测定值与参考值之间差异均较大,因此它们不适合作外标物质.采用BHVO-2G作外标和Si作内标,NIST 610作外标和Zr作内标,Ti含量测定值与参考值之间的差异均小于4％,因此BHVO-2G和NIST 610可有条件地作为外标物质.选择Si还是Zr作内标,GSE-1G作外标时,Ti含量的测定值与参考值之间的差异均小于3％,说明GSE-1G是较为合适的外标物质.选用GSE-1G作为外标,Si作内标,对5个标准锆石中的Ti含量进行了测定,结果显示,Ti元素在锆石91500中分布不均匀,而在锆石GJ-1、M257、PENGLAI和MUDTANK中分布均匀.在Ti元素分布均匀的GJ-1、M257、PENGLAI和MUDTANK等4个锆石中,由于Ti的含量均小于5 μg/g,不适合作为锆石中Ti元素测定用的外标物质,但可作为测定时的质量监控样品.%The Ti content in zircon M257 was determined in-situ by LA-ICP-MS using Si and Zr as internal standards and NIST610, GSE-1G, BHVO-2G, BCR-2G, ATHO-G, KL2-G and Tl-G as external standards. The large difference between measured and referred values by using BCR-2G, ATHO-G, KL2-G and Tl-G as external standards and Si or Zr as internal standard indicated that the four NIST standard materials were not suitable for external materials. Whether using Si as internal and BHV0-2G as external standards, or Zr as internal and NIST 610 as external standards, the difference between measured and referred values was less than 4% , which means that the two standard materials can be used as external standards selectively. Using GSE-1G as the external standard, whether Zr or Si is used as the internal standard, the difference between measured and referred values is less than 3% , which indicates that GSE-1G is a better external standard material. The Ti contents in 5 zircon standards were measured by using Si as internal and GSE-1G as external standards. The Ti distributions were heterogeneous in 91500 and homogeneous in GJ-1, M257, PENGLAI and MUDTANK. However, the Ti contents in the zircon standards of GJ-1, M257, PENGLAI and MUDTANK were less than 5 p,g/g. Therefore all 5 zirconstandards can not be used as external materials because of heterogeneity or lower Ti content, which can only be used as quality control materials in determination of Ti in zircons, except for 91500.