Purity, radiochem

Bromo-7-methyl-6-methylaminoquinoline was nitrated with ACONO2 to give the 6-N(N02)Me derivative, which rearranged in diluted sulfuric acid to the 5-nitro derivative. Reduction of the latter compound, followed by condensation with BrCN and final hydrogenolysis using H2, led to a product of >99% radiochemical purity (85MI1). 

F-Labeled pirenperone (9) was prepared with high radiochemical yield (72%) and high purity (99%) for PET studies from pirenperone using a [ F] fluoride-cryptand-oxalate system (95CL835). 

Muelder and Shadoff (3) prepared C-2,3,7,8-Cl4-DBpD (0.9 mCi/ mmole) by chlorination of C-2,7-dichlorodibenzo-p-dioxin made from potassium C-2,4-dichlorophenate. The preparation of tritium-labeled 2,3,7,8-Cl4-DBpD is justified because the radiolabeled intermediates are less expensive and more accessible and because a higher specific activity is potentially attainable. Here, we consider the optimal conditions for the reaction sequence designed to obtain products of high chemical and radiochemical purity shown at the top of p. 8. 

Tc(V) gluconate and glucoheptonate are often used when the reaction should be carried out in a neutral aqueous- or mixed aqueous/organic medium, and a rapid exchange reaction and high radiochemical purity of the product is required. In radiopharmaceutical preparations, Tc(V) tartrate is also quite often used. For labelling modified antibodies Tc(V) tricine has recently been particularly recommended [33],... 

Cu labeling of TETA proceeded with high radiochemical purity... 

I] 214) 52% radiochemical yield after HPLC, specific activity 27 Ci mmol ( 100% radiochemical purity... 

Typical validation for radiochemical and radiopharmaceutical purity. Quality control is very important to ensure the safety and efficacy of radiopharmaceuticals. One important quality parameter is the radiochemical purity of the radiolabeled product. This is defined as the fraction of the total radioactivity in the desired chemical form in the radiopharmaceutical [56]. Radiochemical impurities come from incomplete labeling, shift of equilibrium, radiolysis ((3 decay), temperature or pH change, exposure to light,... 

Mah, G., Reilly, R. M., Wong, G. L. and Houle, S. A comparison of three methods to determine the radiochemical purity of 99mTc-hexamethylpropylene amine oxime (99mTc-HMPAO). Nucl. Med. Commun. 10 733-740,1989. 

The chemical and radiochemical purity of the labeled compound must be ascertained prior to use. In practice a value of 95% or greater is usually acceptable. The desired specific activity of the administered radioactive compound depends on the dose to be used as well as the species studied. Doses of 14C on the order of 5 pCi/kg for the dog and 20 pCi/kg for the rat have been found adequate in most studies, while doses of 3H are usually two to three times higher owing to lower counting efficiency of this isotope. 

Finally, radiopharmaceuticals are often prepared on a daily basis within the framework of clinical studies which often last several months or years. They demand a viable and reproducible production chain, leading to a sterile- and pyrogen-free radiopharmaceutical of high radiochemical purity. Therefore, microprocessor-controlled automated synthesis devices [31] are developed in order to ensure routine pharmaceutical production. They are becoming mandatory in order to meet the demands related to Good Laboratory Practice (GLP) and Good Manufacturing Practice (GMP). 

F. Fuchtner, P. Angelberger, H. Kvaternik, F. Hammerschmidt, B. Peric-Simovc, J. Steinbach, Aspects of 6-[ F]fluoro-L-DOPA preparation Precursor synthesis, preparative HPLC purification and determination of radiochemical purity, Nucl. Med. Biol. 29 (2002) 477-481. 

Studies of short-lived radionuclide generators (4-6) do not adequately treat the quantitative problems of the daughter nuclide elution or those specific to their optimal clinical use. Two essential physical characteristics of a generator are the yield of the daughter nuclide and its radiochemical and radionuclidic purity. To realize the full potential of a short-lived radionuclide generator for medical studies requires that these two characteristics are optimized and are compatible with parameters important to clinical use such as total perfused volume and duration of the scintigraphic examination. 

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