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Table 3 Separation methods related to the initial target material for getting scandium radionuclides

From: Production of scandium radionuclides for theranostic applications: towards standardization of quality requirements

Starting material Separation Method Reference
TiO2 ion exchange
the AG MP-500 (Bio-Rad) was used after a preliminary treatment in 5 M HNO3 and rinsing with H2O. Ti(IV) was poorly sorbed. Subsequently, scandium was eluted using ammonium acetate
(Pietrelli et al. 1992)
solvent extraction
tri-n-butylphosphate (TBP) was used with an equal volume of 8 N HCl, washed with H2O and a 6% of carbonate solution. Equal volumes of aqueous phase of ion solution and TBP were used.
Cupferron (ammonium salt of the conjugate base derived from N-nitroso-N-phenylhydroxylamine) was also used and Ti(IV) was extracted as cupferrate by 100% chloroform, Sc was separated from Ti by “gravity” with 98% of Sc extracted
(Pietrelli et al. 1992; Valdovinos et al. 2015
extraction chromatography
tri-n-butylphosphate (TBP) was used with an equal volume of 8 N HCl, washed with H2O and a 6% of carbonate solution. Equal volumes of the aqueous phase of ion solution and TBP were used. TBP sorbed onto silica showed that 97.7% of Sc(III) were eluted with 2 mL of HCl 0.1 N. No titanium was detected in the final samples
(Pietrelli et al. 1992)
extraction chromatography
DGA resin could be used for Ti/Sc trace separations in the context of a fine purification of 44Ti from the residual scandium target material. By contrast, ZR® resin was shown to exhibit a high sorption affinity for titanium, whereas scandium could be eluted with HCl solutions. Nonetheless, there are some drawbacks concerning this generator since some breakthrough of 44Ti has been observed after several bed elutions.
(Majkowska-Pilip and Bilewicz 2011)
Ti(0) extraction chromatography
Dissolution in NH4HF2
Elution on a branched DGA resin, recovery of scandium 88%
(Polosak et al. 2013; Loveless et al. 2019b)
CaCO3 extraction chromatography
target dissolved in HCl solution, passed through a UTEVA® resin column and the column washed with HCl. The scandium radionuclides were eluted with H2O. Efficiency 80%
(Valdovinos et al. 2015; Muller et al. 2014)
extraction chromatography
dissolving the CaCO3 targets in HCl solution, passed through a DGA® resin with HCl. Afterwards, the acidic 47Sc solution was passed throught SCX cation exchange cartridges cation and eluted with HCl. Efficiency 93%
(Domnanich et al. 2017a)
extraction chromatography
dissolving the CaCO3 targets in HCl solution, passed through a DGA® resin with HCl. Afterwards, the acidic 43Sc or 44Sc solution was loaded on a column filled with DOWEX50 cation exchange resin and 43Sc or 44Sc was eluted using ammonium acetate solution at pH = 4. Efficiency 75%
(van der Meulen et al. 2015; Muller et al. 2014; van der Meulen et al. 2020)
Ion exchange
dissolution of the target in HCl and adsorption of 43Sc or 44Sc and even 47Sc onto a chelating ion exchange resin Chelex 100. After adsorption of Sc, the column was washed with 0.01 M HCl to remove Ca2+, scandium was eluted with 1 M HCl. Efficiency 70%
(Walczak et al. 2015; Krajewski et al. 2013; Gizawy et al. 2020)
extraction chromatography
loading the dissolved target acidic solution onto DGA®; rinsed in 4 M HCl; HCl was then necessary to elute quantitatively scandium from the DGA® resin. Efficiency 95%
(Chaple and Lapi 2018; Alliot et al., 2015a; Filosofov et al. 2010)
extraction chromatography
dissolution of the target in 9 M HCl, loaded on TBP resin column, 47Sc eluted with H2O. Than loaded onto a BioRad AG50WX4 resin, washed with HCl 0.1 M and H2O; 47Sc was eluted with portions of 1 M sodium acetate solution at pH 4.5. Separation yield 52–79%
(Rotsch et al. 2018)
extraction chromatography
target dissolved in 11 M HCl solution, passed through a UTEVA® resin column. Scandium radionuclides were eluted with H2O and loaded on a BioRad AG50WX4 resin, washed with HCl 0.1 M and 44Sc was eluted with portions of 1 M sodium acetate solution at pH 4.5
Separation yield 93.5%
(Muller et al. 2018)
extraction chromatography
dissolution of the target in 1 mL 2 M HCl, partial neutralization with 0.7 mL 1 M NaOH, pH adjustment with pH 3 formate buffer
loading on Nobias PA-1 (iminobisacetic acid–ethylenediaminetriacetic acid chelate resin) resin column, washing with 2 mL formate buffer, pH 3,
elution with 0.1 mL 2 M HCl, separation yield: 95%
(Kilian et al. 2018)
Precipitation
calcium target dissolved with 2 M HCl, pH adjusted to 6.5–9.0 by addition of 1 M NH4OH, solution pushed through a 0.22 μm Millex-GV 13 mm diameter syringe filter washed with 10 mL 0.1 M NH4OH adjusted to pH 8–9 with HCl.
(Severin et al. 2012)
extraction chromatography
target dissolved in HCl solution, 44Sc was separated from excess of calcium by precipitation of scandium hydroxide using ammonia.
passed through a UTEVA® resin column and the column washed with HCl. The scandium radionuclides were eluted with H2O. Efficiency 80%
(Wojdowska 2019)
electroamalgamation
selective electroamalgamation of Ca2+ ions
(Chakravarty et al. 2017)
precipitation
Dissolution of the target in 1 M HCl, then alkalized with 25% ammonia. Method takes advantage of the insolubility of Sc(OH)3 either as a precipitate or coprecipitate, which can be separated from calcium by using microfilters with PTFE membrane (0.22 μm)
(Minegishi et al. 2016; Severin et al. 2012; Duval and Kurbatov 1953)