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 β- emission with a half-life of 9.392(18) days to stable Tm-169. In addition to β- 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, γ-ray and X-ray emissions are very weak.
The mean electron energy emitted per decay is 103 keV, and 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 production facilities: RHF at ILL or BR2 at SCK CEN.
Distribution
Off-line mass separation is performed at the 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 |
|---|---|
| Production route | Er-168(n,γ)Er-169 |
| Daughter | Decays to stable Tm-169: 100% β- |
| Half-life | 9.39 d |
| Processing | Off-line mass separation + 2-step column separation |
| Primary Container | 2.5 mL borosilicate glass V-vial with silicon rubber screw cap |
| Product Grade | n.c.a. (but not in theoretical molar activity) |
| Physical Form | Liquid |
| Chemical Form | In 0.05 M HCl |
| Radioactive Concentration (gamma spectrometry) | n.a. |
| Appearance | Clear solution |
| Radionuclide identification (gamma spectrometry) | Presence of 110 keV gamma line |
| Radionuclidic Purity (gamma spectrometry) | >99% |
| Chemical purity (ICP-OES) | n.a. |
| Molar activity (ICP-OES) | n.a. |
| Apparent Molar Activity | Labelling at 10 MBq/nmol PSMA-617 |
| Microbiological quality | n.a. |
| Bacterial endotoxin | n.a. |
| pH (pH strips) | n.a. |
| Additional information | |
| Activity available | 100 MBq few times per year (planning in advance), depends on reactor and MEDICIS schedule |
| Activity limit for UN2910 (excepted package) shipment | 1 GBq in dry state or 0.1 GBq in liquid form |
| Other information | Research grade implanted in Al, Zn or NaCl layer on Au foil also possible |