Radiorelease methods

Radiorelease methods are based on the same principle the substance to be determined is brought into contact with another substance containing a radionuchde reagent, and by their interaction a certain amount of the radionuclide is released and measured. For this method substances loaded with Kr (radioactive kryptonates), for example krypton clathrates, may be applied. By reaction with oxygen Kr is released and can be measured continuously. Oxygen dissolved in water can be measured by reaction with jj deposited on Cu 204 jj jg oxidized and released into the... 

Radiochemical methods of analysis can be grouped according to whether one measures radioactivity present in the sample or employs some means of introducing radioactivity into an otherwise nonradioactive sample in order to analyze for some component. An example of the first type is the determination of radioactive in rock samples. The second type is exemplified by using labeled KPO3 (I denoting a radioisotope of iodine) to determine the concentration of SO2 in air by the radiorelease method. This chapter will deal with the use of radioactivity to analyze otherwise nonradioactive substances. 

The second general category of radiochemical analysis involves adding a radioactive substance to the sample, manipulating the sample by chemical or physical means, measuring the radioactivity, and ultimately calculating the amount of the component of interest. This category includes direct and inverse isotope dilution analysis, radiochemical titrations, and radiorelease methods of analysis. 

Radiorelease methods comprising procedures in which the analyte reacts with a radioactive reagent, thus releasing an aliquot of the reagent activity, in most cases into the gas phase. 

In radiorelease methods the analyte substance A reacts with a radioactive reagent, so that radioactive R is released into a second phase, without being replaced by an inactive analyte [62], Applications involve either relea.se of radioreagents from solids or liquids into the gas phase, or release from solids into a liquid. Radiorelease methods may be classified according to the type of the radioactive reagents employed, i.e. (1) radioactive kryptonates, (2) radioactive metals, and (3) radioactive salts and other substances. 

Radiorelease.— Radiorelease methods of analysis are broadly similar to isotope-exchange methods, in that the sample is reacted with a labelled reagent and the redistribution of activity used as a measure of the amount of a particular species in solution. However, the mechanism of the reaction is not simple exchange and, more importantly, the radioisotope need not be of the same element as that to be measured. Thus elements for which radiotracers are not directly available can be measured, e.g. the classical reaction ... 

Many important tracer applications can be substituted by other methods. Even IDA and tracer applications in self-diffusion studies can be replaced by inactive isotope tracer methods using mass spectrometry and other methods for isotope ratio determination. However, because of the extremely high sensitivity of IDA, radioactive tracers are of unique usefulness in radioimmunoassays, radiorelease reagents, radiochromatography, AA, and for systematic studies in trace and ultra-trace analysis, physiological chemistry. IDA, diffusion, isotope exchange, and physical chemistry of solids. 

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