Pertechnetate

The pertechnetate (technetate(VII)) ion is an oxoanion with the chemical formula TcO4&minus;. It is often used as a convenient water-soluble source of isotopes of the radioactive element technetium (Tc). In particular it is used to carry the Tc-99m isotope (half-life 6 hours) which is commonly used in nuclear medicine in several nuclear scanning procedures.

A technetate(VII) is a compound containing this ion. Pertechnetates are salts of technetic(VII) acid. Pertechnetate is analogous to permanganate but it has little oxidizing power.

Use of pertechnetate to carry technetium-99m
A technetium-99m generator, also known as a cow, provides the pertechnetate containing the short-lived isotope Tc-99m for medical uses. This compound is generated directly from molybdate held on alumina within the generator (see this topic for detail). 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. Tc99m-pertechnetate is used for nuclear medicine imaging of the thyroid gland.

Technetate(VII) radiolabeled with Tc99m is also the marker injected into the body looking for ectopic gastric tissue as is found in a Meckel's diverticulum. This nuclear imaging study is otherwise known as a "Meckel's Scan".

Uses of pertechnetate which do not rely on its radioactivity
All technetium salts are mildy 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, Tc-99 (half-life 211,000 years) is used in corrosion research, because it is the decay product of the easily-obtained commercial Tc-99m isotope, which is its nuclear isomer. In theory, the longest-lived technetium isotope, Tc-97 (half-life 2.6 million years), would be the optimal isotope for this use.

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.