RIKEN Accel. Prog. Rep. 50 (2017)

Ⅲ-3. Radiochemistry & Nuclear ChemistryNo-carrier-added puriﬁcation of 28 Mg using co-precipitation andcation exchange method
H. Kikunaga,∗1,∗2 Y. Komori,∗2 H. Haba,∗2 S. Shibata,∗2 and S. Yano∗2∗1∗2

Research Center for Electron Photon Science, Tohoku University
RIKEN Nishina Center- 260 -umn. The 28 Mg isotopes were eluted from the column
with 6 mL of 2 M HCl.
The chemical yield of the separation procedure, determined by γ-spectrometry of 28 Mg, was higher than85%. However, the Mg fraction obtained in the chemical procedure includes a small amount of 7 Be radioactivity. We will attempt to improve this chemical procedure to eliminate Be isotopes from the Mg fraction
completely.
㻠㻜㻟㻡

0.5 M H2C2O4

0.5 M HCl

2 M HCl㻟㻜㻞㻡㻭㼏㼠㼕㼢㼕㼠㼥㻌㻔㼏㼜㼟㻕The isotope 28 Mg is useful in biological sciences as a1,2)
radioactive tracer.
tracer1,2). Generally, 28 Mg is produced foreach use in nuclear reactions because of its short half
3)
life of 21.6 h.
h3). The reaction 27 Al(α,3p)28 Mg is oftenchosen for the production of 28 Mg owing to its potential to produce no-carrier-added 28 Mg tracer with aconvenient and low-cost target. Several groups havereported separation methods of 28 Mg from Al targets
4,5)
6)
adsorption,4,5)
co-precipitation,6)
based on adsorption, co-precipitation, solvent ex7)
method.8)8).
traction7) , and the cation exchange column method
traction,
Although the cation exchange column method should
yield a high purity tracer, it requires a large column
and an eluant volume of a few hundred milliliters. In
this work, we applied a co-precipitation method before
the cation exchange column method to downsize thecolumn volume. Downsizing chemistry leads to the reduction of waste and labor in separation procedures
and the quality improvement of the tracer.
Magnesium-28 was produced in the 27 Al(α,3p)28 Mg
reaction. An α-particle beam was delivered from either
the RIKEN K70 AVF Cyclotron or the AVF Cyclotron
at CYRIC, Tohoku University. The target stack of 7
Al foils (99.9% pure) with a thickness of 100 μm wasirradiated with an α-particle beam with a beam energyof 50 MeV and a mean current of approximately 3 μA.
After the irradiation, the Al targets were dissolved in12 M (mol/dm3 ) HCl diluted with water to 15 mL. The28Mg isotopes were co-precipitated with iron hydroxide by adding 2 mg of Fe(III) and 25 mL of 6 M NaOHand separated from [Al(OH)4 ]− ions. After centrifugal
separation, the precipitation of iron hydroxide was dissolved in 9 M HCl. The solution was passed throughan anion exchange resin column (Dowex 1×8, 100-200
mesh, 1 mL), which adsorbs Fe(III) ions, and the resinwas washed with additional 9 M HCl. The eluate washeated to dryness and adjusted to 0.5 M oxalic acid.
Note that the solution includes non-radioactive Na ionsentering from the co-precipitation process. To investigate the behavior of the Na ions, 300 Bq of 22 Na
tracer was added to the solution. The solution waspassed through a cation exchange resin column (Dowex50w×8, 100-200 mesh, 1 mL) to adsorb 28 Mg isotopes.
The resin was washed with 10 mL of 0.5 M oxalic acidto eliminate Al ions and then with 0.5 M HCl to eliminate Na ions. The elution curves of the cation exchange separation for Na and Mg are shown in Fig. 1.
The Na ions are eluted completely within 10 mL of 0.5
M HCl whereas the Mg ions are retained onto the col-㻞㻜㻌㻞㻞㻺㼍㻌㻞㻤㻹㼓㻝㻡㻝㻜㻡㻜㻜㻝㻜㻞㻜㼂㼛㼘㼡㼙㼑㻌㻔㼙㻸㻕

Fig. 1. Elution curves for the cation exchange separationfor Na and Mg.

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