@misc{oai:repo.qst.go.jp:00067568,
 author = {Muramatsu, Yasuyuki and Yoshida, Satoshi and Sarata, Kumar Sahoo and Matsuzaki, Hiroyuki and Snyder, G. and Fehn, Udo and 村松 康行 and 吉田 聡 and サフー サラタ クマール},
 month = {Oct},
 note = {Iodine-129 (half-life:15.7 Ma) has been released into the environment by nuclear weapons testing and operation of nuclear facilities such as spent fuel reprocessing plants. This nuclide has become widely distributed in the global environment and can be expected, given its long half-life, to behave in similar ways as stable iodine (127I) over long time periods. In the other hand, the 129I/127I ratio can be used in the age determination for geochemical materials (specifically brines). Therefore, it is important to develop appropriate methods in the analysis of both 129I and 127I in environmental materials. In this study, we have examined the following three methods: neutron activation analysis (NAA), accelerator mass spectrometry (AMS) and inductively coupled plasma emission spectrometry (ICP-MS). 
For NAA iodine was separated from the sample by hearting in a quartz tube under oxygen flow. The evaporated iodine was collected in a trap solution containing KOH and K2SO3, followed by purification using solvent extraction. Finally, the iodine fraction was freeze-dried in a small quartz vial, which was irradiated by neutron. After the irradiation, iodine carrier was added and separated from interfering nuclides. Finally, iodine was precipitated as PdI2 and determined 130I and 126I, which were produce by irradiation from 129I and 127I, respectively. The detection limits for 129I and 127I by this method for soil samples (e.g. using 100 g soil) were 0.1 mBq/kg and 0.1 mg/kg, respectively. The 129I/127I ratio of 10-9 could be detected.
For AMS iodine was separated from solid samples also by heating and by solvent extraction similar to the above-mentioned procedure for NAA. However, the amount of samples can be reduced to 1/100 or less, because of the high sensitivity of AMS. In case of liquid samples, iodine was separated by ion-chromatography. For environmental samples, which have high 129I/127I ratios, stable iodine carrier was added in order to lower the ratio in the AMS measurement. Finally iodine was precipitated as AgI, which was used as a target in the determination by AMS. The limit of detection was in the order of 10-14 as 129I/127I ratio.
For ICP-MS water samples were tested to determine 129I. The analytical speed of this method was very high, i.e. 3 minutes for a sample. However, there was a sensitivity limitation for 129I detection due to interference from 129Xe with the 129I peak. The detection limits for 129I and 127I by ICP-MS were 0.5 mBq/mL and 0.1 ng/mL, respectively.
In the presentation we will introduce details of the analytical methods as well as our analytical results for 129I and 127I in environmental and geochemical materials., 放射生態学と環境の放射線被ばくに関する国際シンポジウム},
 title = {Detemination of129I and 127I in environmental samples by NAA, AMS and ICP-MS.},
 year = {2003}
}