LSCE, CEA-CNRS-UVSQ, CEA/Saclay, 91191, Gif-sur-Yvette, France.
J Environ Radioact. 2010 Feb;101(2):185-90. doi: 10.1016/j.jenvrad.2009.10.005. Epub 2009 Nov 10.
The design, setup and performance of a mass spectrometric system for the analysis of low to very low-level tritium in environmental samples are described. The tritium concentration is measured indirectly by the (3)He ingrowth from radioactive decay after complete initial degassing of the sample. The analytical system is fully computer-controlled and consists in a commercial helium isotope mass spectrometer coupled with a high vacuum inlet system. A detection limit of 0.15 Bq/kg is routinely obtainable for sample sizes of 20g of water equivalent and an accumulation time of three months. Larger samples (and/or longer accumulation time) can be used to obtain lower detection limits. In addition to the benefit of a lower detection limit, another advantage of this non-destructive method lies in the simplicity of the analytical procedure which strongly limits the risk of contamination. An inter-comparison was successfully performed with the conventional beta counting technique on lyophilized grass samples, in a range of tritium concentrations of environmental interest. It shows that the (3)He mass spectrometry method yields results that are fully consistent with the conventional liquid scintillation technique over a wide range of tritium concentrations.
描述了一种用于分析环境样品中低至极低水平氚的质谱分析系统的设计、设置和性能。氚浓度通过放射性衰变后完全初始除气的样品中（3）He 的生长来间接测量。分析系统完全由计算机控制，由与高真空入口系统耦合的商业氦同位素质谱仪组成。对于 20g 水当量的样品量和三个月的积累时间，通常可以获得 0.15 Bq/kg 的检测限。可以使用更大的样品（和/或更长的积累时间）来获得更低的检测限。除了更低的检测限的好处之外，这种非破坏性方法的另一个优点在于分析程序的简单性，这大大降低了污染的风险。在氚浓度环境感兴趣的范围内，对冻干草样品成功地进行了与传统β计数技术的比较。结果表明，在氚浓度广泛的范围内，（3）He 质谱法与传统的液体闪烁技术完全一致。
