同位素稀释-负热表面电离质谱法分析土壤样品中的超微量^(99)Tc  

Determination of Trace Technetium-99 in Soil Samples by Isotope Dilution/Negative Thermal Ionization Mass Spectrometry

作　　者：汤磊[1] 王丽雄[1] 刘雪梅[1] 龙开明[1] 杨通在[1] 熊宗华[1] 龚建[1] 

机构地区：[1]中国工程物理研究院核物理与化学研究所,四川绵阳621900

出　　处：《核化学与放射化学》2012年第5期310-315,共6页Journal of Nuclear and Radiochemistry

摘　　要：为了定量测定土壤样品中的超微量99Tc,发展了Tc的放化分离纯化流程和负热电离质谱分析技术,自行制备了97Tc稀释剂。建立了土壤样品中超微量Tc的放化分离流程,全流程Tc化学回收率为71%。采用天然Ru粉在高通量反应堆中辐照,提取并标定了97Tc稀释剂(同位素丰度:97Tc,84.77%;98 Tc,15.03%;99 Tc,0.20%)。由于Tc具有极高的电离电位(7.3eV),采用热表面电离质谱(TIMS)难以测量,因此研究了Tc的负热电离质谱分析技术(NTIMS)。对比研究了4种发射剂,使用MgCl2+Ba(OH)2负离子发射剂,Tc标准样品的99 TcO4-(M/z=163)离子流强度可以达到1.7×10-12A。采用该定量分析技术对土壤样品进行了99Tc的定量测定,合成标准不确定度好于3%。As an important long-lived and high-abundance fission product,99Tc dispersed into the environment because of the nuclear test in atmosphere,the nuclear fuel cycle and nuclear medicine.The isotope dilution mass spectrometry（IDMS）technology of measuring 99Tc using 97Tc as the spike was developed.The chemical separation procedure of Tc is established,and the recovery rate is more than 71% for the overall process.97Tc（97Tc,84.77%;98Tc,15.03%;99Tc,0.20%）was prepared by irradiation of natural ruthenium metal,then was calibrated by IDMS with 99Tc standard material as the spike.The conventional positive thermal ionization mass spectrometry（TIMS） was inapplicable due to the high ionization potential of 7.3 eV for technetium,therefore based on MgCl2＋Ba（OH）2 as the loading reagent,the negative thermal ionization mass spectrometry of technetium was established,and the ion current indensity of 99TcO-4（M/z=163） reached 1.7×10-12 A.Then,99Tc in the soil samples was quantitatively determined by negative thermal ionization mass spectrometry and isotope dilution method.The combined standard uncertainty is better than 3%.

关 键 词：99Tc 负热电离质谱 同位素稀释法 97Tc 

分 类 号：O657.6[理学—分析化学]