Development of chemical separation method for the measurement of Cs/Cs isotopic ratio in environmental samples

Shimada, Asako ; Nomura, Masao*; Tsukahara, Takehiko*; Takeda, Seiji 

Although identification of radiocesium in environmental samples is commonly performed by using Cs/Cs radioactivity ratio, measurement of Cs will become challenge in a few decade ago because of short half-life (2 y). Instead of the measurement of Cs/Cs radioactivity ratio, the measurement of Cs/Cs isotopic ratio will be effective in future because of long half-life of Cs (133 My). In order to measure Cs/Cs isotopic ratio, Cs must be separated from the matrix of soil. Since 1 Bq of Cs is equal to 312.5 fg, large amount of soil have to be treated to extract Cs for the measurement. In the present study, we improved chemical separation method using BOBCalixC6 by optimizing extraction time and reuse of the organic phase. Finally, approximately 170 g of soil sampled at Toka-mura was dissolved and Cs was separate with the developed method to measure Cs/Cs isotopic ratio.