RADIOCHEMICAL METHODS IN ANALYSIS

Emission of ionizing radiations in radioactive decay, nuclear particle and y-ray spectrometry. Quantitative and qualitative analysis by intensity and spectrometric measurements respectively. 

Gas ionization, solid scintillation, liquid Scintillation and semiconductor detectors, autoradiography. Single pnd - multichannel pulse height analysers. Coincidence and anticoigoide nce circuits. 

Study of chemical pathways in method development. Isotope dilution methods. Radioimmunoassay very important in biochemistry and medicine. Neutron activation analysis used Tor trace elements in geochemistry, semiconductor technology, pollution studies and forensic science. Relative precision of counting 1 % if 104 counts are recorded. 

Sometimes expensive for tracers or irradiation facilities. Special laboratory and handling facilities required. Needs highly skilled operators, and complex instrumentation. 

Three main features account fpr the usefulness of radiotracers in analysis. Firstly, a chemical species may be labelled with a radioactive atom and thus 

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D. I. Comber, Radiochemical Methods in Analysis, Plenum Press, London, 1975. 

Bowen, H. J. M., and Gibbons, D., Radioactivation Analysis, Oxford University Press, London, 1963. Coomber, D. I. (ed.). Radiochemical Methods in Analysis, Plenum Press, New York, 1975. 

A text with a scope similar to this book is Radiochemical Methods in Analysis (Coomber 1975). The text contains such relevant chapters as Separation methods for inorganic species and The use of tracers in inorganic analysis. A chapter titled Determination of radioactivity present in the environment contains information geared toward sample collection. 

Coomber, D. I. 1975. Radiochemical Methods in Analysis. New York, NY Plenum Press. Coplan, M. A., Moore, J. H., and Hoffman, R. A. 1984. Double-focusing ion mass-... 

Three common quantitative applications of radiochemical methods of analysis are considered in this section the direct analysis of radioactive isotopes by measuring their rate of disintegration, neutron activation, and the use of radioactive isotopes as tracers in isotope dilution. 

Radiochemical methods of analysis take advantage of the decay of radioactive isotopes. A direct measurement of the rate at which a radioactive isotope decays may be used to determine its concentration in a sample. For analytes that are not naturally radioactive, neutron activation often can be used to induce radioactivity. Isotope dilution, in which a radioactively labeled form of an analyte is spiked into the sample, can be used as an internal standard for quantitative work. 

The following instrumental analysis textbooks may be consulted for further information on the detectors and signal analyzers used in radiochemical methods of analysis. 

Activation analysis, the application of radiotracers and other radiochemical methods in innovative trace analysis are indispensable, first of all in the preparation of standard reference samples. 

Fukai, R. 1965. Analysis of trace amounts of chromium in marine organisms by the isotope dilution of Cr-51. Pages 335-351 in Radiochemical Methods of Analysis. Int. Atom. Ener. Agen. (Vienna). 

Rybach, L. and Nissen, H.U. (1964). Neutron activation of Mn and Na traces in marbles worked by the Ancient Greeks. In Proceedings of Radiochemical Methods of Analysis. International Atomic Energy Agency, Vienna, pp. 105-117. 

International Atomic Energy Agency Radiochemical Methods of Analysis-Proceedings of the Symposium on Radiochemical Methods of Analysis held in Salzburg, Austria, October, 1964. Vienna International Atomic Energy Agency 1965. 

Radiochemical Methods in Analytical Chemistry. Activation Analysis with Gamma-Ray Photons and Charged Particles. Chimica 21, No. 3, 116 (1967). 

G. R. Gilmore, Radiochemical Methods of Analysis, in Radiochemistry, Vol. 1, Specialist Periodical Reports, The Chemical Society, London, 1972. 

Radiochemical methods of analysis are considerably more sensitive than other chemical methods. Most spectral methods can quantitate at the parts-per-mil-lion (ppm) level, whereas atomic absorption and some HPLC methods with UV, fluorescence, and electrochemical methods can quantitate at the parts-per-billion (ppb) levels. By controlling the specific activity levels, it is possible to attain quantitation levels lower than ppb levels of elements by radiochemical analyses. Radiochemical analysis, inmost cases, can be done without separation of the analyte. Radionuclides are identified based on the characteristic decay and the energy of the particles as described in detection procedures presented above. Radiochemical methods of analysis include tracer methods, activation analysis, and radioimmunoassay techniques. 

Gibbons D and Lambie DA (1971) Radiochemical methods of analysis. In WBson CL and WBson DW, eds. Comprehensive analytical chemistry, Vol 2C, Electrical methods, physical separation methods, pp. 130—205. Elsevier, Amsterdam. 

Radiochemical methods of analysis employ radioactivity, with or without chemical manipulations, to obtain qualitative or quantitative information about the composition of materials. This information may concern the nature and quantity of elements or the specific chemical form of the component of interest. For example, qualitative and quantitative determinations of elements present in river waters can be readily accomplished on the other hand, radiochemical methods can be used to determine the quantity of vitamin B12 (which contains an atom of cobalt) in a mixture of similar organic compounds. The fundamental difference between this method of analysis and all others is that, in this method, one either induces radioactivity in the sample or adds a radioactive substance to the sample. 

Radiochemical methods of analysis are used in a wide range of analytical applications. Not only can these methods be used to obtain information regarding the nature and quantities of substances present in materials of interest, but radioactive elements can also be employed as tracers to study various physicochemical processes. Radioactive substances can be used to follow the movement of elements or of specific compounds in soils and plants, the absorption of elements in the body, and the selfdiffusion of lead atoms in metallic lead, among other applications. Although these tracer applications are of great practical value, the present chapter will be concerned only with applying radioactivity to determining the presence and quantity of elements and compounds in various materials—that is, the use of radioactivity in chemical analysis. 

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. 

In summarizing the results of FDMS in the analysis of metals, the following principal facts emerge. Although the area of metal trace analysis is covered by a number of well-established analytical techniques, such as the mass spectrometric variants described in this chapter but also spectroscopic, electrochemical and radiochemical methods, in a number of cases the use of FDMS has become attractive because of the following characteristics ... 

It was therefore possible to study the time course of iodocompound-pro-cessing activities in brain through application of straightforeward radiochemical methods of analysis. 

The radiochemical methods of analysis to be discussed in this chapter will be divided into two groups for convenience tracer methods will be defined as those methods where the radioisotope is introduced into the analytical technique independently of the sample, and activation methods those where the radioisotope is incorporated into the sample by nuclear reaction. The different types of method may each have advantages in a particular situation, depending upon the availability of particular isotopes, the concentration at which the method is to be applied, and the instrumental facilities available to the individual analyst. 

The present volume covers the areas of Solid State Recoil Chemistry, the Radiochemistry of Elements with Z > 103, and Radiochemical Methods of Analysis, for the period July 1969 to July 1971. In Volume 2 it is intended to extend this coverage and include Gas Phase Recoil Chemistry and High Energy Nuclear Reactions. 

N.Ikeda et al published a new radiochemical method for analysis of iodide and iodate in environmental water Radioisotopes,lXi 91V Z). 

There are many potential advantages to kinetic methods of analysis, perhaps the most important of which is the ability to use chemical reactions that are slow to reach equilibrium. In this chapter we examine three techniques that rely on measurements made while the analytical system is under kinetic rather than thermodynamic control chemical kinetic techniques, in which the rate of a chemical reaction is measured radiochemical techniques, in which a radioactive element s rate of nuclear decay is measured and flow injection analysis, in which the analyte is injected into a continuously flowing carrier stream, where its mixing and reaction with reagents in the stream are controlled by the kinetic processes of convection and diffusion. 

Although similar to chemical kinetic methods of analysis, radiochemical methods are best classified as nuclear kinetic methods. In this section we review the kinetics of radioactive decay and examine several quantitative and characterization applications. 

Isotope Dilution Another important quantitative radiochemical method is isotope dilution. In this method of analysis a sample of analyte, called a tracer, is prepared in a radioactive form with a known activity. Ax, for its radioactive decay. A measured mass of the tracer, Wf, is added to a sample containing an unknown mass, w, of a nonradioactive analyte, and the material is homogenized. The sample is then processed to isolate wa grams of purified analyte, containing both radioactive and nonradioactive materials. The activity of the isolated sample, A, is measured. If all the analyte, both radioactive and nonradioactive, is recovered, then A and Ax will be equal. Normally, some of the analyte is lost during isolation and purification. In this case A is less than Ax, and... 

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