Lead determination radiochemical methods

This article presents a comprehensive view of the present state-of-the-art of radiochemical separations for the following trace elements in coal Hg, Rb, Cs, Se, Ga, As, Sb, Br, Zn, Cd, and U. Most of the work on the determination of trace elements in coal is very recent. The accuracy of the analysis methods, nearly all newly developed, has been open to question because of the lack of standards and lack of knowledge of the range of concentrations for many trace elements in coal. Federal government laboratories have taken the lead in evaluating methods of analysis and in developing standards. By a round-... 

The study of reaction rates presents difficulties not encountered in investigations concerned only with the original and final states of a chemical system. The progress of a reaction can be followed by (a) physical methods such as the observation of changes in electrical conductance, colour, volume, ultra-violet absorption or optical activity, or the measurement of the gas evolved, (b) chemical methods leading to the determination of reactants and products, (c) radiochemical methods in which the transfer of radioactive material is observed. 

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. 

One of the main differences between radiochemical analytical procedures and classical analytical methods is that the element (and particularly its radioisotope) to be determined is present in the sample in minor to trace amounts. Separation of radionuclides is performed with the aid of a suitable carrier. Generally, the carrier is a stable isotope (or a suitable compound) that is added to the radioactive compound in a small but detectable amount and has identical chemical properties. An isotopic carrier, i.e., a stable isotope of the element in question, is most frequently used. Both the radioactive isotope and the carrier must be in the same chemical form. The isotopic carrier is irreversibly mixed with the radioactive compound and cannot be separated from it again by chemical means. Such a carrier can therefore be used only when a lower specific activity is sufficient for the subsequent operations. For example, barium or lead can serve as carriers when... 

---