负热电离质谱法测量Os同位素组成的质量分馏校正  

Mass Fractionation Correction of Osmium Isotopic Compositions in Negative Thermal Ionization Mass Spectrometric Measurement

作　　者：郑磊[1] 支霞臣[1] 靳永斌[1] 

机构地区：[1]中国科学技术大学地球和空间科学学院,安徽合肥230026

出　　处：《质谱学报》2004年第4期193-197,共5页Journal of Chinese Mass Spectrometry Society

基　　金：中国科学院知识创新工程项目 (KZCXZ- 10 7);国家重点基础研究发展规划项目 (G19990 75 5 0 3);国家自然科学基金资助项目 (4 0 1730 0 9;4 98730 0 5 )

摘　　要：根据质量分馏校正和氧同位素干扰校正的原则 ,通过实践总结出一套处理数据的方法 ,包括不加稀释剂条件下采用美国 Finnigan MAT公司的推荐值 2 40 M/2 3 6M=3 .0 92 2 0 3 ,与本工作提出的归一化值 2 40 M/2 3 8M=1 .5 5 3 62 4进行质量分馏校正。理论上本实验室提出的归一化基准值适用于各种类型岩矿样品 ,该值与样品的 187Os/188Os比值无关。加稀释剂条件下采用循环迭代的方法 ,在每次迭代过程中得到新的归一化基准值 ,并进行氧同位素校正和质量分馏校正 ,最后得到样品的 Os含量和 187Os/188Os的值 ,实践表明通常情况下在 5～ 6次迭代后即可收敛 。The methods of mass fractionation correction and oxygen isotope interference correction in the processing of measuring osmium isotopic compositions by negative thermal ionization mass spectrometry are described. The methods based on the practice of processing data were applicable for unspiked and spiked cases. In the former case the normalization factors of 240M/ 236M= 3.092 203 given by Finnigan MAT company and 240M/ 238M=1.553 624 recommended in the laboratory were used for mass fractionation correction, respectively. It suggested that the value suggested is independent on 187Os/ 188Os ratio of sample in study, so that it's applicable for various types of sample. In the latter case, the new normalization value with iterative algorithm method will be obtained in each iterative step and used for mass fractionation correction and oxygen isotope interference correction at the same time. The convergent results of osmium concentration and 187Os/ 188Os ratio for the sample can be calculated through five or six iterative steps based on practical data processes.

关 键 词：质量分馏校正 负热电离质谱(NTIMS) Os同位素 归一化值 

分 类 号：O657.63[理学—分析化学] O614.824[理学—化学]