Recent Developments in Simultaneous C14 and Tritium Counting
Since all biological, organic material contains carbon and hydrogen, radioactive isotopes of these two elements have proven to be very important in tracing the course of metabolites in biological systems. The simultaneous use of C14- and H3-tagged metabolites under identical experimental conditions greatly extends the usefulness of tracer methodology in various field of research. In biochemistry, double-labeled nutrients permit the study of the incorporation of a C14-labeled compound and a tritiated labeled compound in the same experiment. This can be accomplished either by labeling two parts of the same molecule, as in the case of tritiated methyl-labeled acetate and carboxyl-labeled acetate (acetate-1-C14), or by introducing two different metabolites in the same experiment as glucose-U-C14 and tritiated acetate . Another type of double-label experiment is one in which the turnover of a product and the incorporation of precursors into the product can be measured in the same experimental animals . In pharmacology the metabolic fate of a drug labeled with both C14 and tritium can be followed . When the drug is labeled in two different positions of the molecule, changes in the C14: H3 ratio indicate that specific activity can be used for analysis where the isotope-derivative or dilution-derivative methods are employed . These procedures are of particular value for the estimation of components of a mixture of related compounds for which individual chemical methods of analysis are not available. It should be noted that the accuracy of these methods of assay are independent of loss of material.
KeywordsLiquid Scintillation Gain Control Balance Point Gain Setting Machine Setting
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