Analysis of Krypton-85 and Krypton-81 in a Few Liters of Air

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• 作者：Le-Yi Tu ; Guo-Min Yang ; Cun-Feng Cheng ; Gu-Liang Liu ; Xiang-Yang Zhang ; Shui-Ming Hu
• 刊名：Analytical Chemistry
• 出版年：2014
• 出版时间：April 15, 2014
• 年：2014
• 卷：86
• 期：8
• 页码：4002-4007
• 全文大小：293K
• 年卷期：v.86,no.8(April 15, 2014)
• ISSN：1520-6882

文摘

Long-lived radioactive krypton isotopes, ⁸¹Kr (t_1/2 = 229鈥?00 year) and ⁸⁵Kr (t_1/2 = 10.76 year), are ideal tracers. ⁸¹Kr is cosmogenic and can be used for dating groundwater beyond the ¹⁴C age. ⁸⁵Kr is a fission product and can be applied in atmospheric studies, nuclear safety inspections, and dating young groundwater. It has long been a challenge to analyze radio-krypton in small samples, in which the total number of such isotopes can be as low as 1 脳 10⁵. This work presents a system developed to analyze ⁸¹Kr and ⁸⁵Kr from a few liters of air samples. A separation system based on cryogenic distillation and gas chromatographic separation is used to extract krypton gas with an efficiency of over 90% from air samples of 1鈥?0 L. ⁸⁵Kr/Kr and ⁸¹Kr/Kr ratios in krypton gases are determined from single-atom counting using a laser-based atom trap. In order to test the performance of the system, we have analyzed various samples collected from ambient air and extracted from groundwater, with a minimum size of 1 L. The system can be applied to analyze ⁸¹Kr and ⁸⁵Kr in environmental samples including air, groundwater, and ices.