Daughters from parents, generation

We used a similar approach to generate daughters from parents (Figure 25.5). Strategic bond cleavage gives us daughters that can be used in a library format with various cores. 

Ion exchange and solvent extraction techniques have been used extensively as the basis for radiochemical generators exploiting the differences in absorption behavior between the parent nuclide and its useful daughter nuclide. Many parent/daughter pairs of nuclides have sufficiently different polarographic half wave potentials so that their electrochemical behavior may be exploited for rapid separation of the daughter from the parent with minimal contamination of the product with the parent isotope. ... 

Elution Methods. For every generator, the separation of the daughter nuclide from the parent can be performed by the continuous (steady state) method or the discontinuous (bolus) method. The continuous method involves the elution of the daughter nuclide from the generator as it is formed and direct administration as a gas or liquid phase. The bolus method involves the elution at one time of the available daughter... 

Handling samples obtained in solution is more straightforward. The solutions are usually in DMSO, stored frozen between +4 and -20 °C. Automated plate duplication and cherry-picking of individual wells are now commonplace procedures. Thus, end users are not forced to accept all compounds from a specific plate, since the ability to generate daughter plates from parents is a simple matter. Samples can be dispensed into any compatible well-based system, such as monoblocks or cluster tubes, or 96-well plates can be combined to create higher density plates. The use of solution-phase samples also allows a significant reduction in deliverable sample sizes, often... 

Instrnments combining several analyzers in sequential order are very common. This combination allows mass spectrometry and mass spectrometry experiments (MS/MS) to be carried out. Modern MS/MS includes many different experiments designed to generate substructural information or to qnantitate componnds at trace levels. A triple quadru-pole mass spectrometer allows one to obtain a daughter ion mass spec-trnm resnlting from the decomposition of a parent ion selected in the first qnadrnpole. The MS/MS experiments using an FTICR or ion trap, however, are carried ont in a time-resolved manner rather than by spatial resolntion. 

This paper is directed at illustrating the feasibility of exploiting differences in the electrochemistry of parent/daughter nuclide pairs to produce useful generator systems. The decay of a parent nuclide to its daughter involves a move from one row of the periodic table to an adjacent row. Frequently, there are drastic differences in the electrochemical nature of adjacent rows of the periodic table. Examples of such differences are shown in Table II. In each of the listed cases, the elements may be separated from one another by careful control of a potential applied to a suitable electrode. 

A radionuclide generator can be described as a parent-daughter pair from which the daughter nuclide is separated from the parent in as pure a nuclear form as possible throughout the operating life of the system. A variety of publications (1-3) have emphasized the general principles of the medical use and qualitative aspects of radionuclide generators. The most frequent example discussed is the Mo-99/Tc-99m system. 

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