Chemical properties
Er-169 is a radiolanthanide, usually in trivalent state. The ionic radius of Er3+ is 89 pm, i.e. just 3% larger than Lu3+, which explains that chelators suitable for Lu-177 can be directly employed for Er-169 too, in particular DOTA.
Nuclear properties
Er-169 decays by beta-minus emission with a half-life of 9.392(18) days to stable Tm-169. In addition to beta-minus emission it shows emission of low energy conversion and Auger electrons , thus emitting in total about 1.45 electrons (with energies above 6 keV) per decay. However, gamma ray and X-ray emission is very weak.
The mean electron energy emitted per decay is 103 keV, the mean photon energy per decay is <1 keV .
Production
Er-169 is produced by thermal neutron irradiation of enriched Er-168 oxide targets in the high flux reactors of the PRISMAP production facilities: RHF at ILL or BR2 at SCK CEN.
Distribution
Off-line mass separation is performed at the PRISMAP production facility MEDICIS (CERN, Geneva, Switzerland). Activity will be shipped from there to the users in form of ErCl3 solution or in solid form, implanted into an Al, Zn or NaCl layer.
| Parameter | Specifications |
|---|---|
| Half-life | 9.39 d |
| Daughter | Stable Tm-169 |
| Branching Ratio/Decay | 100% β- |
| Production | Er-168(n,𝛾) Er-169 |
| Purification | Off-line mass separation + 2-step column separation |
| Chemical Form | In 0.05 M HCl |
| Specific Activity | n.a. |
| Radionuclidic Purity | >99% |
| Radiochemical Purity | n.a. |
| Chemical Purity | n.a. |
| Identification | Presence of 109.8 keV gamma line |
| Appearance | Clear solution |
| pH | 1-2 |
| Activity available | 100 MBq |
| Availability | Few times per year (planning in advance), depends on reactor and MEDICIS schedule |
| Grade | preclinical, n.c.a. |
| Other information | Research grade implanted in Al, Zn or NaCl layer on Au foil also possible |