The separation of tin-113 and indium-113 m by thin layer chromatographic method

Abstract

The separation of ^113mIn from a mixture of ¹¹³Sn-^113mIn in a radioactive equilibrium was carried out by a thin layer chromatographic method using silicagel as the adsorbent and diluted acetic acid as the developer. At first, the separation of non radioactive Sn(II), Sn(IV) and In(III) ions were tested by using various concentrations of acetic acid solutions. By increasing the concentration of acetic acid, a higher R_f value for In(III) was obtained. On the contrary, Sn(IV) was retained at the original point and Sn(II) advanced with tailing because it was oxidized to Sn(IV) during the development. Accordingly, in order to let Sn stay at the origin, Sn(II) must be oxidized to Sn(IV) by adding H₂O₂ into the sample solution before the development. The best separation of Sn and In were obtained by the solvent consisting of acetic acid: water (1 : 10), by which the R_f values were 0.00 for Sn(IV) and 0.90 for In(III).
The spread of Sn (IV) spot was investigated by using sample solutions at various HCl concentration. Sn(IV)spread with increasing the HCl concentration, while In(III) spot stayed at the position of R_f value 0.90 irrespective of the HCl concentration. Accordingly, in order to obtain a clear separation of the spots of these two ions, the HCl concentration of the sample solution must be adjusted at about 1 N.
The development could be achieved within about 20 minutes by raising the developing solvent 5 cm high from the original point.
^113mIn was separated from ¹¹³Sn by applying the method mentioned above. The radiochemical purity of the ^113mIn which was scratched from the developed plate was identified to be more than 99.9% by analyzing its decay curve, about 93% of it was extracted from the adsorbent by 5 ml of an acetic acid : water mixture (1:10).