199Au

Au 199

3.14 d

β^- 0.3, 0.5...

γ 158, 208...

Chemical properties

Au-199 is usually in trivalent state.

Nuclear properties

Au-199 decays by β^- emission with a half-life of 3.139(7) days to stable Hg-199. It emits a low energy β^- spectrum with 82 keV average energy and 452 keV maximum energy. In addition to β^- emission it emits low energy conversion and Auger electrons , thus emitting in total about 1.42 electrons (with energies above 7 keV) per decay. Hence, Au-199 is a β^--emitter with half-life similar to Sc-47, but low energy electron spectrum, similar to Er-169 or Tb-161.

Moreover Au-199 emits γ-rays at 158.4 keV (40%) and 208.2 keV (8.72%), making it suitable for SPECT-imaging (possibly requiring high-energy collimators in presence of Au-198 admixture).

The mean electron energy emitted per decay is 112 keV, the mean photon energy per decay is 95 keV .

Production

Carrier-added Au-199 is produced by double neutron capture on Au-197 targets in the high flux reactor RHF at ILL. This production route leads to co-production of Au-198.

Distribution

Irradiated targets are dissolved and separations are performed at Hevesy Laboratory (DTU, Risø, Denmark). Activity will be shipped from there to the users in form of AuCl₃ solution.

Examples of use

In a comparison of 22 different β^- emitters Au-199 showed the most localized energy deposition with a dominant dose below 1 mm distance ,.
Dose distributions of Au nanoparticles containing Au-198 or Au-199 have been calculated .
Preclinical in vivo SPECT imaging with mixed Au-198/Au-199 radiotracers has been reported .
Au-199 has been used for radiolabeling and SPECT imaging of Au nanoparticles . Radioisotopes of gold are the optimum choice for this purpose since in vivo stability is naturally assured.
Radiolabeling of antibodies with Au-199 has been reported .

Purity grades available

research

preclinical

No carrier added (n.c.a.)

Parameter	Specifications
Production route	Au-197(n,γ)Au-198(n,γ)Au-199
Daughter	Decays to stable Hg-199: 100% β^-
Half-life	3.14 d
Processing	1-step separation
Primary Container	2.5 mL borosilicate glass V-vial with silicon rubber screw cap
Product Grade	n.c.a.
Physical Form	Liquid or dried deposit
Chemical Form	In 0.05 M HCl
Radioactive Concentration (gamma spectrometry)	n.a.
Appearance	Clear solution
Radionuclide identification (gamma spectrometry)	158 keV and 208 keV gamma lines present
Radionuclidic Purity (gamma spectrometry)	80-90% (also 10-20% Au-198)
Chemical purity (ICP-OES)	n.a.
Molar activity (ICP-OES)	About 1 GBq/µmol (0.06% of theoretical maximum)
Apparent Molar Activity	n.a.
Microbiological quality	Bioburden and endotoxin burden can be analysed post release, upon request
Bacterial endotoxin	Bioburden and endotoxin burden can be analysed post release, upon request
pH (pH strips)	n.a.
Additional information
Activity available	Few GBq few times per year (planning in advance), depends on reactor schedule
Activity limit for UN2910 (excepted package) shipment	0.6 GBq in dry state or 60 MBq in liquid form (combined Au-199 and Au-198 activity)
Other information	Au-198 : half-life 2.69 days, medium energy β-decay and emission of 412 keV (95.62%) γ-rays. For future needs the alternative production of n.c.a. Au-199 (higher molar activity and free of Au-198 admixture) could be considered