在大量同质异位素干扰下的同位素稀释质谱法测定173Lu和174Lu

当2种以上元素在热表面电离质谱计（TIMS）蒸发带表面蒸发时，蒸气中各元素的比例随着蒸发带加热电流的变化而变化，相应质量数处离子流的比值也随之发生变化。据此原理，建立了大量同质异位素干扰下的同位素分析方法。该方法的可靠性在同质异位素干扰量为1 000倍的情况下得到了实验验证。结合该方法和热表面电离同位素稀释质谱法（ID-TIMS）分析了大量¹⁷³Yb和¹⁷⁴Yb干扰下放射性核素¹⁷³Lu和¹⁷⁴Lu在溶液中的浓度，¹⁷³Lu和¹⁷⁴Lu合成标准不确定度分别为0.45%和1.1%。

Measurement of Radioactive Isotope 173Lu and 174Lu With Yb Isobars by ID-TIMS

When more than two elements on the filament of a thermal ionization mass spectrometer (TIMS) are vaporized, the element ratios in the vapor depend on the filament temperature. The ion current ratios of different mass numbers vary with the temperature, which is dominated by the filament current. With the presence of isobaric interference, the method of isotopic analysis by TIMS is established in the present paper and applied to determine the natural lutetium abundance in the solutions, in which ytterbium and lutetium are mixed by ratio of 1 000∶1. The measured isotope ratio of lutetium is in good agreement with the standard value. Likewise, the concentrations of ¹⁷³Lu and ¹⁷⁴Lu in the real samples produced through bombardment of ytterbium target by proton beam are determined by ID-TIMS. The relative uncertainties of concentrations are 0.45% and 1.1%, respectively. 