Chemical properties
Sc-44 is a rare earth, usually in trivalent state. It can be radiolabelled with macrocyclic chelators, e.g. DOTA or other chelators such as NODAGA, AAZTA, pypa, mpatcn, etc. . The ionic radius is 74.5 pm.
Nuclear properties
Sc-44 decays by beta-plus emission (94.27(5)%) and electron capture (5.73%) with a half-life of 4.042(25) hours to stable Ca-44. It emits a medium energy positron spectrum with 632 keV average energy and 1474 keV maximum energy.
Moreover, Sc-44 emits a hard gamma-ray at 1157.0 keV (99.9%) in prompt coincidence (T1/2=2.7 ps) with every emitted positron.
The mean electron energy emitted per decay is 596 keV, the mean photon energy per decay is 2136 keV .
Production
Sc-44 is produced by proton irradiation of enriched Ca-44 oxide (or carbonate targets) at: Injector 2 at PSI or C30 cyclotron at NCBJ. ARRONAX uses instead deuteron irradiation .
Distribution
The radiochemical separations are performed at ARRONAX (ARRONAX, Nantes, France), PSI Radiochemistry Laboratory (PSI, Villigen, Switzerland) or POLATOM (NCBJ, Otwock-Swierk, Poland). Activity will be shipped from there to the users in form of ScCl3 (or acetate) solution, ready for labelling of e.g. DOTA-compounds.
Examples of use
Parameter | Specification |
---|---|
Half-life | 4.04 h |
Daughter | Stable Ca-44 |
Branching Ratio/Decay | 94.3% β+, 5.7% EC |
Production | Ca-44(p,n)Sc-44 [or Ca-44(d,2n)Sc-44 at ARRONAX] |
Purification | 1 or 2 steps column separation |
Chemical Form | In 0.05 M HCl, 0.1 M HCl, 4.85 M NaCl/0.13 M HCl or 1 M NaOAc |
Specific Activity | 2 GBq/mg |
Radionuclidic Purity | 99.8% (0.2% Sc-44m) |
Radiochemical Purity | Labelling up to 25 MBq/nmol DOTANOC or DOTATATE |
Identification | 1157 keV gamma line present |
Appearance | Clear and colourless solution |
pH | Depends on chemical form |
Activity available | Up to 1 GBq |
Availability | On demand |
Grade | Research grade or preclinical grade, n.c.a. |