Preparation radio-labelled compounds

The results show that the addition of 5 mg of HABA to l-DOTATATE stabilizes the preparation, allowing high radiochemical purity of the radio-labelled compound to be maintained for 6 d at 4-8°C. 

Together with details of sample preparation and storage, an appropriate analytical method of known accuracy, precision, and sensitivity must be available for the quantification of the substance in the test solution and in the biological material. If these are lacking it is impossible to determine a true BCF. The use of radiolabelled test substance can facilitate the analysis of water and fish samples. However, unless combined with a specific analytical method, the total radioactivity measurements potentially reflect the presence of parent substance, possible metabolite(s), and possible metabolized carbon, which have been incorporated in the fish tissue in organic molecules. For the determination of a true BCF it is essential to clearly discriminate the parent substance from possible metabolites. If radiolabelled materials are used in the test, it is possible to analyse for total radio label (i.e. parent and metabolites) or the samples may be purified so that the parent compound can be analysed separately. 

The isotope used to prepare labelled compounds is obtained by irradiation in a nuclear reactor, of solid targets containing atoms of nitrogen (aluminium or beryllium nitride), by neutrons of low energy, known as thermal neutrons, themselves the product of the controlled atomic fission of The radiocarbon formed is next isolated from the target sample by oxidation to Ba " 003, the variety in which it is delivered to chemists. From C02, it is possible to use a plethora of organic chemical reactions to synthesize different compounds in which the radio-isotope can be introduced to a specific position. 

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