upported ionic liquid phases for extraction and separation of medical radiolanthanides - Towards purification of medical samarium-153

Promovendus/a: Michiel Van de Voorde

Promotor(en): Prof. dr. Koen Binnemans, Dr. Thomas Cardinaels

Radioistopes are an important tool in nuclear medicine, where they are deployed for treatment of different types of cancer and for imaging. Several elements of the lanthanide series have isotopes that serve well in nuclear medicine because of their advantageous decay properties. Some of these radiolanthanides are even suitable for theranostics because they simultaneously emit particles suitable for therapy and photons for imaging. Most often, these radiolanthanides also decay into a stable daughter radionuclide, limiting the backgroud radiation of the patient after treatment.

Radiolanthanides can be efficiently produced in a nuclear reactor by bombardment of a (enriched) target with neutrons. Depending on the production strategy followed, the resulting radiolanthanide can be removed chemically from the target material (non-carrier-added, n.c.a.) or can not separated from the target material (carrier-added, c.a.). Radiochemical processing of the targets after irradiation is needed to obtain sufficiently high specific activities for targeted radiotherapy (in case of n.c.a.), or to obtain sufficiently high radionuclidic purity (in case of c.a.).

In this project, the main focus was put on the removal of long-lived Eu-154 radionuclidic purities from c.a. produced Sm-153, to extend the shelf-life of Sm-153 radiopharmaceuticals. The amount of Eu-154 allowed in the final Sm-153 radiopharmaceutical is limited, and is strictly regulated.

A new and innovative separation method for samarium and europium was developed in the scope of this project. In a first step, Eu(III) is reduced to its divalent state in concentrated nitrate salt solution, after which Sm(III) is selectively extracted to an ionic liquid phase in a second step. Sm(III) can be easily back-extracted to an aqueous phase by water, i.e. reducing the total salt concentration in the system. This way, a simple yet efficient separation method was established. After development of the solvent extraction method, the approach was translated to the use of supported ionic liquid phases (SILPs), where the ionic liquid is immobilised on a solid support. These SILPs can be used as stationary phase in extraction chromatography, and have already proven to be able to separate Sm(III) and Eu(II). The developed method shows high potential for being applied in radiochemical processing of medical Sm-153.