Ⅲ-3. Radiochemistry & Nuclear Chemistry

RIKEN Accel. Prog. Rep. 51 (2018)

Trial of astatine separation using column chromatography
H. Ikeda,∗1,∗2,∗3 H. Kikunaga,∗2,∗3 Y. Komori,∗3 S. Yano,∗3 T. Yokokita,∗3 H. Haba,∗3 and H. Watabe∗1

∗1
∗2
∗3

Cyclotron and Radioisotope Center, Tohoku University
Research Center for Electron Photon Science, Tohoku University
RIKEN Nishina Center- 227 -Table 1. Results of batch experiment (ratio of At%).

   㽢

Fig. 1. Separation method of At using column chromatography (filler: activated carbon).



Astatine (At) is one of the nuclides expected to be
applied for targeted α-particle therapy (TAT). Several
methods for At separation are known, but mainly twomethods (dry distillation1) and wet extraction2,3) ) areused. Dry distillation can obtain yield a pure solution of At, however complicated apparatus must beconstructed.1) On the other hand, although wet extraction is a simple method, the aqueous solution iscontaminated with an organic solvent after back extraction. In order to apply At for TAT, the separation
method has be improved further. In this work, column
chromatography was attempted as one of the improved
methods.
We produced 211 At at RIKEN Nishina Center using
the 209 Bi(α, 2n)211 At reaction (29 MeV, 250 particle
nA, 30 min) and 210 At at Cyclotron and Radioisotope Center (CYRIC), Tohoku University using the209Bi(α, 3n)210 At reaction (50 MeV, 100 particle nA,30 seconds). A bismuth oxide (Bi2 O3 ) pellet was usedas the target. The irradiated target was dissolved in
2 mL of 4 M HCl containing 1 M NaHSO3 , and 6 mLof 0.84 M EDTA·2Na solution was added (stock solution).
Batch experiments of 5 fillers (anion-exchange resin,cation exchange resin, activated carbon, alumina, andcellulose) were conducted, in which 0.1 mL of fillers
were added to 1 mL of stock solution. These mixtures were shaken for 5 min and centrifuged for 10 min.
The fillers and supernatant was separated and theirradioactivity were measured (Table 1). A significant
amount of At was adsorbed on anion exchange resin
and activated carbon, however little At was adsorbedon the other fillers.
We attempted column chromatography using anionexchange resin and activated carbon. 1 mL of stocksolution was charged into a filler (5 mmϕ × 4 mm), andthe column was eluted. In both cases, almost all At
was trapped in the column. Trapped At was not elutedby concentrated HCl. However, At on the activatedcarbon column was eluted by 10 M NaOH solution.
Thus we optimized the separation method (Fig. 1) anddrew the elution curve (Fig. 2). In the experiment,
85% of charged At was eluted by 10 column volumesof 10 M NaOH solution. It is suggested that At isoxidized to AtO(OH) at pH 14 which is the conditionof the eluent.4) This result suggested that AtO(OH) donot adsorbed on activated carbon. We could harvest
high yield At easily.
However, the At solution was strongly alkaline.























Fig. 2. Elution curve of At from activated carbon column.

Therefore, it is not possible to use this solution forbiological research (pre-clinical and clinical research).
In the future, we plan to test the removal method ofconcentrated cations, consider another target dissolution method, and apply other fillers.
References
1) S. Lindegren et al., Appl. Radiat. Isot. 55, 157 (2001).
2) M. S. Sultana et al., J. Radioanal. Nucl. Chem. 243,631 (2000).
3) C. Zona et al., J. Radioanal. Nucl. Chem. 276, 819(2008).
4) J. Champion et al., Inorg. Chim. Acta. 362, 2654
(2009).