Pertechnetate
[5] Some metals like actinides,[7] barium, scandium, yttrium [8] or zirconium [9] may form complex salts with pertechnetate thus strongly effecting its liquid-liquid extraction behavior.
99Mo can be produced in a nuclear reactor via irradiation of either molybdenum-98 or naturally occurring molybdenum with thermal neutrons, but this is not the method currently in use today.
As the 99Mo continuously decays to 99mTc, the 99mTc can be removed periodically (usually daily) by flushing a saline solution (0.15 M NaCl in water) through the alumina column: the more highly charged 99MoO2−4 is retained on the column, where it continues to undergo radioactive decay, while the medically useful radioisotope 99mTcO−4 is eluted in the saline.
The half-life of 99mTc is long enough that labelling synthesis of the radiopharmaceutical and scintigraphic measurements can be performed without significant loss of radioactivity.
A majority of radiopharmaceuticals labelled with 99mTc are synthesized by the reduction of the pertechnetate ion in the presence of ligands chosen to confer organ specificity of the drug.
The resulting 99mTc compound is then injected into the body and a "gamma camera" is focused on sections or planes in order to image the spatial distribution of the 99mTc.
After a scanning is performed, it is recommended that a patient drink large amounts of water in order to expedite elimination of the radionuclide.
The starting material Na[99mTcO4], made available after elution from the generator column, as mentioned above, can be reduced in the presence of complexing ligands.
The radiopharmaceutical must be kinetically inert, in that it must not change chemically in vivo en route to the target organ.
Since technetate(VII) can substitute for iodine in the Na/I symporter (NIS) channel in follicular cells of the thyroid gland, inhibiting uptake of iodine into the follicular cells, 99mTc-pertechnetate can be used as an alternative to 123I in imaging of the thyroid, although it specifically measures uptake and not organification.
[17] It has also been used historically to evaluate for testicular torsion, although ultrasound is more commonly used in current practice, as it does not deliver a radiation dose to the testes.
It is also used in labeling of autologus red blood cells for MUGA scans to evaluate left ventricular cardiac function, localization of gastrointestinal bleeding prior to embolization or surgical management, and in damaged red blood cells to detect ectopic splenic tissue.
In particular, 99Tc (half-life 211,000 years) is used in corrosion research, because it is the decay product of the easily obtained commercial 99mTc isotope.
[3] Solutions of technetate(VII) react with the surface of iron to form technetium dioxide, in this way it is able to act as an anodic corrosion inhibitor.
