The 16th International Conference on Accelerator Mass Spectrometry

Iodine, as an essential biophilic element, is widely present in living organisms and crucial for human life activities. Among iodine isotopes, only iodine-127 is a stable nucleus, while iodine-129 has the longest half-life (1570 million years). Therefore, it is particularly important to isolate iodine from soil samples and utilize AMS to measure the ratio of iodine-129 to iodine-127 for analyzing the level of environmental nuclear contamination. In this study, a method involving the addition of a carrier to precipitate iodine as silver iodide forming milligram-level iodine targets was developed. Using a tube furnace to generate high temperatures, iodine was volatilized from soil samples, and the released iodine vapor was collected with an alkaline trapping solution. 1 mg of carrier iodine was added to the trapping solution, and all iodides were reduced to iodide ions through oxidation-reduction reactions. A 1 ml solution was taken for stable iodine measurement using ICP-MS. Adding silver nitrate to the solution produced a precipitate. Impurities in the precipitate were dissolved and washed away with ammonia solution to obtain silver iodide precipitate. The precipitate was dried, mixed with niobium powder, pressed into a target, and measured with AMS to obtain the ratio of the two isotopes. This method can accurately determine the ratio of iodine-129 to iodine-127 content, with broad potential applications in environmental monitoring and geological dating.