Er 169
9.39 d
β- 0.3...
γ (110...)

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 .


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.


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.

Purity grades available


No carrier added (n.c.a.)

Available in n.c.a. form (but not in theoretical specific activity)
Production routeEr-168(n,γ)Er-169
DaughterDecays to stable Tm-169: 100% β-
Half-life9.39 d
ProcessingOff-line mass separation + 2-step column separation
Primary Container2.5 mL borosilicate glass V-vial with silicon rubber screw cap
Product Graden.c.a. (but not in theoretical molar activity)
Physical FormLiquid
Chemical FormIn 0.05 M HCl
Radioactive Concentration (gamma spectrometry)n.a.
AppearanceClear 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)Labelling at 10 MBq/nmol PSMA-617
Apparent Molar Activityn.a.
Microbiological qualityn.a.
Bacterial endotoxinn.a.
pH (pH strips)n.a.
Additional information
Activity available100 MBq few times per year (planning in advance), depends on reactor and MEDICIS schedule
Activity limit for UN2910 (excepted package) shipment1 GBq in dry state or 0.1 GBq in liquid form
Other informationResearch grade implanted in Al, Zn or NaCl layer on Au foil also possible


  • β-therapy

Point of supply

  • Geneva, Switzerland

Involved production facilities

ILL, France
CERN, International
SCK CEN, Belgium