激光共振电离质谱法测量锡的同位素比  

Measurement of Tin Isotope Ratios by Laser Resonance Ionization Mass Spectrometry

作　　者：沈小攀[1] 李志明[1] 王文亮[1] 翟利华[1] 邓虎[1] 徐江[1] 韦冠一[1] 汪伟 

机构地区：[1]西北核技术研究所,西安710024

出　　处：《分析化学》2017年第3期342-347,共6页Chinese Journal of Analytical Chemistry

基　　金：国家重大科学仪器设备开发专项项目(No.2012YQ250003)资助~~

摘　　要：采用实验室研制的激光共振电离质谱仪,建立了锡(Sn)同位素的激光共振电离质谱分析方法。测量了锡原子的自电离态光谱,确认了锡的一条三色三光子共振电离路径,其各步激发/电离的激光波长分别为λ_1=286.4 nm、λ_2=811.6 nm、λ_3=823.7 nm;通过将样品与氧化石墨烯溶液混合制样,有效提高了锡样品的电热原子化效率,1μg锡的总探测效率达到3×10^(-5)以上,是直接滴样方式的4.5倍左右。采用本方法对锡、锑、碲(1∶1∶1,m/m)混合模拟样品进行测试,实现了锡的选择性电离,有效避免了测量过程中锑、碲对锡的同量异位素干扰,样品中主要同位素比^(116)Sn/^(120)Sn,^(117)Sn/^(120)Sn,^(118)Sn/^(120)Sn和^(119)Sn/^(120)Sn测量的相对标准偏差均<1%。结果表明,本方法能够有效解决TIMS、ICP-MS等商业质谱仪在锡同位素质谱分析过程中的同量异位素干扰难题,有望应用于反应堆乏燃料中裂变产物^(121)mSn、^(126)Sn的测量。A preliminary method based on the laser resonance ionization mass spectrometer （LRIMS） developed in the laboratory was established to determine tin isotope ratios. By measuring the auto-ionization spectrum of tin atoms, a three-color-three-photon resonance ionization scheme was confirmed, and the laser wavelengths of each excitation/ionization step were A1 =286.4 nm, A2 =811.6 nm and A3 =823.7 nm. More effective electrothermal atomization of tin was implemented by mixing the samples and grapheme oxide solution, and the total detection efficiency of 1 μg of tin sample was above 3×10-5, which was about 4.5 times as high as the method of directly dropping samples. A tin-antimony-tellurium mixture at a ratio of 1 ： 1 ： 1 （m/m） was prepared as a simulant sample, and the major tin isotope ratios in the sample were determined. Results showed that the isobaric interference from antimony and tellurium was effectively avoided, and the relative standard deviations for 116Sn/120Sn, 117sn/120Sn, 118Sn/120Sn, 119Sn/120Sn were all better than 1%. This work indicated that LRIMS could effectively avoid the isobaric interference in the measurement of tin isotope ratios, and could be applied to measure the fission product 121mSn and 126Sn in the reactor spent fuel.

关 键 词：激光共振电离质谱 锡 同量异位素干扰 同位素比 元素选择性 

分 类 号：O657.63[理学—分析化学]