Technetium-99m (99mTc) is an everlasting radionuclide, which has seen the birth of the Nuclear Medicine and that the recent advances gained in technetium chemistry, coupled to improvement in detector technologies, still continue to make it useful and competitive, compared to the trendy PET radionuclides. Moreover, also thanks to studies and technologies which have been developed in the framework of the INFN CSN5- funded, APOTEMA and TECHN-OSP projects (2012- 2017) aimed at ensuring a new route in cyclotron-based production of 99mTc, even the shortage issues occurred in the last ten years, due to the ageing of the reactor-based production chain mainly, may be overcome. In this framework, an automatic module for the extraction, separation and purification of the 99mTc from the molybdenum metal target, based on the solvent extraction technique, was developed by our group in collaboration with the radiopharmacy unit of the Sant’Orsola Hospital. This system exploits a helium-bubbling into a separation column to boost the solvent extraction of technetium into a biphasic system, composed by an alkaline aqueous solution (containing Tc, Mo and contaminants) and an organic phase of methyl ethyl ketone (MEK). The developed system, although revealed very efficient, may however be improved in processing times and costs. Indeed, both dissolution and extraction-separation are the time- consuming steps of the whole procedure (about 20 and 30 minutes respectively over a total of 60 min). Moreover, the module developed consists of an assembly of commercially-available modular units overall quite expensive (i.e. in the range 50-80 k€). Therefore, with the aim to overcome those issues and improve our system as well, a different way of automation was investigated about the solvent extraction step. Currently, the technology trend underway, aimed at achieving of a compact-size system, is leading to the development of micro-scale reactors (lab-on-chip) also in the field of radiochemical separation, in order to improve performance and minimize chemical and radiological risks [6]. In this view, we selected a membrane-based separator device, Liquid-Liquid Separator Sep – 10 (Figure 1), patented and produced by ZAIPUT Flow Technologies company (Cambridge, Massachusetts, USA), in order to automate the solvent extraction and separation process of technetium from molybdenum in an in-flow chemistry regime. This device allows to effectively separate two immiscible phases by exploiting the interfacial tension and the affinity of one of the two phases for a microporous membrane (PTFE). Thanks to a differential pressure applied inside the device by a diaphragm, the separation can take place continuously. The in-flow extraction process carried out at micro-scale level adds some advantages when compared to similar processes performed on a macro-scale, including: shorter extraction times, an increase in the mass transfer coefficient, a better surface-volume interface ratio (S/V), etc.

New developments on the extraction and separation of cyclotron-produced Tc-99m from molybdenum metal target

P. Martini
Primo
;
L. Uccelli;M. Giganti;A. Duatti;A. Boschi
Ultimo
2020

Abstract

Technetium-99m (99mTc) is an everlasting radionuclide, which has seen the birth of the Nuclear Medicine and that the recent advances gained in technetium chemistry, coupled to improvement in detector technologies, still continue to make it useful and competitive, compared to the trendy PET radionuclides. Moreover, also thanks to studies and technologies which have been developed in the framework of the INFN CSN5- funded, APOTEMA and TECHN-OSP projects (2012- 2017) aimed at ensuring a new route in cyclotron-based production of 99mTc, even the shortage issues occurred in the last ten years, due to the ageing of the reactor-based production chain mainly, may be overcome. In this framework, an automatic module for the extraction, separation and purification of the 99mTc from the molybdenum metal target, based on the solvent extraction technique, was developed by our group in collaboration with the radiopharmacy unit of the Sant’Orsola Hospital. This system exploits a helium-bubbling into a separation column to boost the solvent extraction of technetium into a biphasic system, composed by an alkaline aqueous solution (containing Tc, Mo and contaminants) and an organic phase of methyl ethyl ketone (MEK). The developed system, although revealed very efficient, may however be improved in processing times and costs. Indeed, both dissolution and extraction-separation are the time- consuming steps of the whole procedure (about 20 and 30 minutes respectively over a total of 60 min). Moreover, the module developed consists of an assembly of commercially-available modular units overall quite expensive (i.e. in the range 50-80 k€). Therefore, with the aim to overcome those issues and improve our system as well, a different way of automation was investigated about the solvent extraction step. Currently, the technology trend underway, aimed at achieving of a compact-size system, is leading to the development of micro-scale reactors (lab-on-chip) also in the field of radiochemical separation, in order to improve performance and minimize chemical and radiological risks [6]. In this view, we selected a membrane-based separator device, Liquid-Liquid Separator Sep – 10 (Figure 1), patented and produced by ZAIPUT Flow Technologies company (Cambridge, Massachusetts, USA), in order to automate the solvent extraction and separation process of technetium from molybdenum in an in-flow chemistry regime. This device allows to effectively separate two immiscible phases by exploiting the interfacial tension and the affinity of one of the two phases for a microporous membrane (PTFE). Thanks to a differential pressure applied inside the device by a diaphragm, the separation can take place continuously. The in-flow extraction process carried out at micro-scale level adds some advantages when compared to similar processes performed on a macro-scale, including: shorter extraction times, an increase in the mass transfer coefficient, a better surface-volume interface ratio (S/V), etc.
2020
Martini, P.; Uccelli, L.; Pasquali, M.; Giganti, M.; Duatti, A.; Esposito, J.; Boschi, A.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11392/2434282
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