Chemical properties
In solution Hg-197 is divalent (Hg2+), a soft Lewis acid that binds strongly to sulfur-donor ligands; sulfur-rich macrocyclic chelators such as a cyclen-based tetrathiol ligand and DO4S have been developed for stable Hg2+ radiolabelling of tumour-targeting vectors REF.
Nuclear properties
Hg-197 decays with a half-life of 64.14 h by 100% electron capture to Au-197. It emits 23.2 Auger electrons with energy ranging from 40 eV to 70 keV. It has a very weak γ emission at 191.4 keV (0.63%) but it is emitting X rays at 67 keV (56.3%) and 78 keV (31.1%) that can be easily measured REF.
Hg-197m is a metastable state of Hg-197 with a half-life of 23.8(2) h that decays at 91.4 % to the Hg-197 ground state and 8.6% directly by b+/electron capture to Au-197. It emits a 133.97(4) keV γ ray with a branching ratio of 34.1(5)% that can be used for SPECT imaging. It also emits 19.4 Auger electrons with energy ranging from 40 eV and 80 keV.
Production
Hg-197m/Hg197 are produced by irradiation of a gold target by either a proton beam At HZDR REF or a 16 MeV deuteron beam at ARRONAX REF.
Distribution
Radiochemistry is done at ARRONAX (Nantes, France) or at Institute of Radiopharmaceutical Cancer Research (HZDR, Dresden, Germany). Activity will be shipped in the form of HgCl2 solution or HgCl2/HgAc2 solution, respectively.
Examples of use
Hg-197 has been identified as a possible Auger emitter of interest REF,REF.
| Parameter | Specifications |
|---|---|
| Production route | Au-197(p,n)Hg-197 or Au-197(d,2n)Hg-197 |
| Daughter | Hg-197m decays to Hg-197 by IT and partially also to Au-197 by EC, Hg-197 decays to stable Au-197 by EC |
| Half-life | Hg-197m (23.8 h) – Hg-197 (64.1 h) |
| Processing | Extraction chromatography and multi-step evaporation |
| Primary Container | Plastic vial or 3.0 mL borosilicate glass V-vial with silicon rubber screw cap |
| Product Grade | n.c.a. |
| Physical Form | Liquid |
| Chemical Form | Hg2+ ion in HCl (<0.1 M) or acetate solution |
| Radioactive Concentration (gamma spectrometry) | 600 MBq per ml |
| Appearance | Clear colourless solution |
| Radionuclide identification (gamma spectrometry) | 77 keV and 191 keV gamma lines present |
| Radionuclidic Purity (gamma spectrometry) | >99% |
| Chemical purity (ICP-OES) | n.a. |
| Molar activity (ICP-OES) | n.a. |
| Apparent Molar Activity | n.a. |
| Microbiological quality | n.a. |
| Bacterial endotoxin | n.a. |
| pH (pH strips) | Depends on chemical form |
| Additional information | |
| Activity available | ~200 MBq EOI (more to be discussed) |
| Activity limit for UN2910 (excepted package) shipment | 10 GBq Hg-197/0.4 GBq Hg-197m in dry state or 1 GBq Hg-197/0.04 GBq Hg-197m in liquid form |
| Other information |
