Pertechnetate

1) Pertechnetate, which is actively transported (as an iodide analog) into the thyroid. 

2) Hepatobiliary agents, such as 33 Tc(HlDA)2 which is actively accumulated by hepatocytes. 

Many attempts have been made to design labeled compounds 

Molecules which are strongly bound to serum proteins may be limited to an intravascular volume of distribution even if they are small enough to diffuse through membrane pores or lipid soluble enough to diffuse directly through the lipoidal membrane itself. In some cases, protein binding will not completely eliminate distribution in the extracellular and intravascular compartments since it may only delay diffusion into these compartments.  

ACS Symposium Series American Chemical Society Washington, DC, 1980. 

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Technetium is a silvery-gray metal that tarnishes slowly in moist air. The common oxidation states of technetium are +7, +5, and +4. Under oxidizing conditions technetium (Vll) will exist as the pertechnetate ion, TcOr-. The chemistry of technetium is said to be similar to that of rhenium. Technetium dissolves in nitric acid, aqua regia, and cone, sulfuric acid, but is not soluble in hydrochloric acid of any strength. The element is a remarkable corrosion inhibitor for steel. The metal is an excellent superconductor at IIK and below. 

H3POS peroxomonophosphoric acid HTCO4 pertechnetic acid... 

There are three general types of radiopharmaceuticals elemental radionucHdes or simple compounds, radionucHde complexes, and radiolabeled biologically active molecules. Among the first type are radionucHdes in their elemental form such as Kr and Xe or Xe, and simple aqueous radionucHde solutions such as or I-iodide, Tl-thaUous chloride, Rb-mbidium(I) chloride [14391-63-0] Sr-strontium(II) chloride, and Tc-pertechnetate. These radiopharmaceuticals are either used as obtained from the manufacturer in a unit dose, ie, one dose for one patient, or dispensed at the hospital from a stock solution that is obtained as needed from a chromatographic generator provided by the manufacturer. 

Many kits contain the indicated biologically active ingredient in a lyophilized form with stannous chloride. A Tc-labeled radiopharmaceutical, which can be used for six hours, is formed when mixed with Tc pertechnetate. Preparation of the agent is at room temperature, unless otherwise stated. Technetium-99m. Available Tc kits are Hsted below. 

Technetium-9 9m sestamibi is used in myocardial perfusion imaging for the evaluation of ischemic heart disease. It is prepared from a lyophilized kit containing tetrakis(2-methoxy isobutyl isonittile) copper(I) tetrafluoroborate stored under nitrogen. Upon reconstitution with up to 5.6 GBq (150 mCi) of 99mTc pertechnetate, the product is formed by boiling for 10 minutes. 

Technetium-99m disofenin is used for hepatobiliary imaging. Disofenin (2,6-diisopropylphenylcarbamoyhnethyliminodiacetic acid) is the active ingredient. Product formation is accompHshed by addition of up to 3.7 GBq (100 mCi) of Tc pertechnetate. 

Technetium-99m albumin coUoid is cleared by the reticuloendothehal (RE) cells and is used for visualization of the RE system of the Hver, spleen, and bone marrow. The product is formed by the addition of up to 2.8 GBq (75 mCi) of Tc pertechnetate. 

Technetium-99m pyrophosphate is used for bone imaging. The compound appears to have an affinity for the hydroxyapatite crystals within bone, and is formed by addition of up to 7.4 GBq (200 mCi) pertechnetate. 

Technetium-99m mertiatide (A/-[Ai-[A/-[(benzoylthio)acetyl]glycyl]glycine) is a renal imaging agent. It is excreted by the kidneys via active tubular secretion and glomerular filtration. The kit vial is reconstituted by using 740—3700 MBq (20—100 mCi) of Tc pertechnetate and boiling for 10 minutes. 

Early studies on oxide films stripped from iron showed the presence of chromium after inhibition in chromate solutionand of crystals of ferric phosphate after inhibition in phosphate solutions. More recently, radio-tracer studies using labelled anions have provided more detailed information on the uptake of anions. These measurements of irreversible uptake have shown that some inhibitive anions, e.g. chromateand phosphate are taken up to a considerable extent on the oxide film. However, other equally effective inhibitive anions, e.g. benzoate" pertechnetate and azelate , are taken up to a comparatively small extent. Anions may be adsorbed on the oxide surface by interactions similar to those described above in connection with adsorption on oxide-free metal surfaces. On the oxide surface there is the additional possibility that the adsorbed anions may undergo a process of ion exchange whereby... 

Nitridotechnetium phthalocyanine (PcTcN) is prepared in a melt of phthalonitrile and ammonium pertechnetate (NH4Tc04). The axial nitrido ligand has its origins from the ammonium ion.250... 

Momoshima et al. [19,20] developed an analytical procedure to determine "Tc in sea water by ICP-MS. "Tc was concentrated from the original sea water by the steps of filtration, reduction of pertechnetate with K2S2O5, co-precipta-... 

Chemical separation of technetium in soils is not easy, but it is fairly well-known that under aerobic conditions pertechnetate Tc(YII) is readily transferred to plants while under anaerobic conditions insoluble TcCh (or its hydrate) is not transferred to them. Even under aerobic conditions, however, the transfer rate decreases with time [28], indicating that soluble pertechnetate changes to insoluble forms by the action of microorganisms which produce a local anaerobic condition around themselves [29,30]. Insoluble technetium species may be TcOz, sulfide or complexes of organic material such as humic acid. 

In a recent study of the complexation of technetium with humic acid (HA) Sekine et al. [34,35] obtained interesting results which show competition between Tc,v-0(0H) i precipitate formation and Tcin-HA precipitate formation during a reduction process of pertechnetate with Sn2+. A weighable amount of... 

Halides form with Tc(V) both neutral compounds, such as TcOX3 (X = F, Cl, Br), and oxohalide anions. Fluoride differs from the other halides by forming KTcF6 [18], For X = Cl and Br, simple oxohalotechnetates [TcOX4] are accessible in a reaction of pertechnetate with concentrated acids HX according to... 

Further reduction to the Tc(IV) species, [TcX6]2, is slow compared with their rapid formation from pertechnetate. This fact, as well as trapping by precipitation with large organic cations, allows isolation of the thermodynamically less favoured TcOX4 anions. 

All [TcOX4] spedes hydrolyse in aqueous solution and then disproportionate into pertechnetate and Tc(IV) oxide hydrate according to... 

A general mode of access to polyhydric complexes of Tc(V) is reduction of pertechnetate with two equivalents of stannous chloride in aqueous solution of the excess O-donor ligand, e.g. ... 

Complexation studies with bidentate phosphine ligands showed that stable cationic complexes of Tc(V), Tc(III), and Tc(I) are easily accessible. The influence of reaction conditions on reaction route and products is well demonstrated by the reaction of pertechnetate with the prototype 1,2-bis(dimethylphosphino)-ethane (dmpe) (Fig. 16). Careful control of reduction conditions allows the synthesis of [Tc02(dmpe)2]+, [TCl2(dmpe)2]+, and [Tc(dmpe)3]+, with the metal in the oxidation states V, III, and I [120,121]. This series illustrates the variety of oxidation states available to technetium and their successive generation by the action of a 2-electron reducing agent. 

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