Determination of Ultralow Level 129I/127I in Natural Samples by Separation of Microgram Carrier Free Iodine and Accelerator Mass Spectrometry Detection

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• 作者：Xiaolin Hou ; Weijian Zhou ; Ning Chen ; Luyuan Zhang ; Qi Liu ; Maoyi Luo ; Yukun Fan ; Wangguo Liang ; Yunchong Fu
• 刊名：Analytical Chemistry
• 出版年：2010
• 出版时间：September 15, 2010
• 年：2010
• 卷：82
• 期：18
• 页码：7713-7721
• 全文大小：187K
• 年卷期：v.82,no.18(September 15, 2010)
• ISSN：1520-6882

文摘

Separation of carrier free iodine from low iodine level samples and accurate measurement of ultralow level ¹²⁹I in micrograms of iodine target are essential but a bottleneck in geological dating of terrestrial system and tracer research using naturally produced ¹²⁹I. In this work, we present a carrier free method using coprecipitation of AgI with AgCl for preparing micrograms of iodine target, associated with combustion using a tube furnace for separating iodine from solid samples and anion exchange chromatography for preconcentrating iodine from a large volume of water. An accelerator mass spectrometry was used to measure ultralow level ¹²⁹I in micrograms of iodine target. The recovery of iodine in the entire separation procedure is higher than 80% and 65% for solid and water samples, respectively. One microgram iodine in the target (AgI−AgCl) can produce a stable ¹²⁷I signal for AMS measurement of ¹²⁹I/¹²⁷I, and a detection limit of this method for ¹²⁹I is calculated to be 10⁵ atoms. This will allow us to accurately determine ¹²⁹I in prenuclear geological samples of low iodine concentration with ¹²⁹I/¹²⁷I of 10⁻¹², such as loess, soil, coral, rock, sediment, and groundwater. Some samples with low iodine content have been successfully analyzed, and the lowest value of the ¹²⁹I/¹²⁷I ratio of 2 × 10⁻¹¹ was observed in 23.5 and 63.5 m loess samples collected in the Loess Plateau, China. The developed method sheds light on a wide application in earth science.