Pertechnetate

is the starting material for most of the chemistry of technetium. Pertechnetate salts are usually colorless. is produced by oxidizing technetium with nitric acid or with hydrogen peroxide. The pertechnetate anion is similar to the permanganate anion but is a weaker oxidizing agent. It is tetrahedral and diamagnetic. The standard electrode potential for / is only +0.738 V in acidic solution, as compared to +1.695 V for /. Because of its diminished oxidizing power, is stable in alkaline solution. is more similar to . Depending on the reducing agent, can be converted to derivatives containing Tc(VI), Tc(V), and Tc(IV). In the absence of strong complexing ligands, is reduced to a +4 oxidation state via the formation of hydrate. barium, scandium, yttrium or zirconium may form complex salts with pertechnetate thus strongly effecting its liquid-liquid extraction behavior. ==Preparation of 99mTcO4−==

is conveniently available in high radionuclidic purity from molybdenum-99, which decays with 87% probability to . The subsequent decay of leads to either or . 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. Currently, is recovered as a product of the nuclear fission reaction of , separated from other fission products via a multistep process and loaded onto a column of alumina that forms the core of a / radioisotope generator. As the continuously decays to , the 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 is retained on the column, where it continues to undergo radioactive decay, while the medically useful radioisotope is eluted in the saline. The eluate from the column must be sterile and pyrogen free, so that the Tc drug can be used directly, usually within 12 hours of elution. ==Compounds==

• Radiolysis of in nitrate solutions proceeds through the reduction to which induces complex disproportionation processes: : {{chem2|TcO4^{-} + e^{-} -> TcO4^{2-} }} :{{chem2|2TcO4^{2-} -> TcO4^{-} + Tc^{V} }} :{{chem2|2Tc^{V} -> TcO4^{2-} + Tc^{IV} }} :{{chem2|Tc^{V} + TcO4^{2-} -> Tc^{IV} + TcO4- }} • Pertechnetate can react with H2S to give Tc2S7. • Pertechnetate is also reduced to Tc(IV/V) compounds in alkaline solutions in nuclear waste tanks without adding catalytic metals, reducing agents, or external radiation. Reactions of mono- and disaccharides with 99m yield Tc(IV) compounds that are water-soluble. ==Uses==

Pharmaceutical use The half-life of is long enough that labelling synthesis of the radiopharmaceutical and scintigraphic measurements can be performed without significant loss of radioactivity. Other methods of administration include intraperitoneal, intramuscular, subcutaneous, as well as orally. The behavior of the ion is essentially the same, with small differences due to the difference in rate of absorption, regardless of the method of administration. Synthesis of 99mTcO4− radiopharmaceuticals is advantageous for the synthesis of a variety of radiopharmaceuticals because Tc can adopt a number of oxidation states. 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 autologous 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. It is actively accumulated and secreted by the mucoid cells of the gastric mucosa, and therefore, technetate(VII) radiolabeled with technetium-99m is injected into the body when looking for ectopic gastric tissue as is found in a Meckel's diverticulum with Meckel's scans. Non-radioactive uses All technetium salts are mildly radioactive, but some of them have explored use of the element for its chemical properties. In these uses, its radioactivity is incidental, and generally the least radioactive (longest-lived) isotopes of Tc are used. 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. ==See also==