CHAPTER 10 



RADIOACTIVATION ANALYSIS 



Principles Sensitivity. Sources of Radiation. Procedures. Biological 

 Applications— Arsenic; Sodium and Potassium; Gold; Cobalt; Strontium; Rare 

 Earths. Miscellaneous Applications 



The discovery of artificial radioactivity in 1934 and the availabihty of 

 methods for the production of artificial radioisotopes have led to a truly 

 novel method of analysis. In principle, the sample to be analyzed is 

 placed in a flux of bombarding particles long enough for the production of 

 a measurable amount of a radioisotope of the element to be determined. 

 After elimination of radiocontaminants by one means or another, meas- 

 urement of the induced radioactivity provides a determination of the 

 amount of the particular element in the sample. 



References to the early work in the field are documented in the general 

 references (1 to 7), particularly in the review of Boyd (1). Hevesy and 

 Levi, perhaps the first workers to use the method, in 1936-1938 estimated 

 dysprosium in samples of yttrium, and europium in gadolinium, with the 

 avoidance of the difficult rare-earth chemical separations. Seaborg and 

 Livingood in 1938 demonstrated galUum contamination in iron after bom- 

 bardment of the latter in the cyclotron. King and Henderson in 1939 

 detected traces of copper in silver, and Sagane et al. in 1942 estimated 

 sodium in aluminum. Ardenne and Bernard in 1944 used an electrostatic 

 accelerator to determine carbon in steel. Tobias (8) and Brues and 

 Robertson (9) in 1947 employed the method for the determination of 

 trace elements in biological tissue. Clark and Overman (10) in 1947 

 reported studies using the Oak Ridge chain-reacting pile and ('oined the 

 term radioadivation analysis, which is sometimes abbreviated in usage to 



activation analysis. 



A primary advantage of activation analysis is the extreme sensitivity 

 for many elements which exceeds that of conventional chemical and phys- 

 ical methods. Besides the inherent sensitivity in the production and 

 detection of radioactivity, the over-all sensitivity may be increased by the 

 use of relatively large samples. Contamination problems are virtually 

 nonexistent since, after the bombardment has been completed, the results 

 are independent of any contamination by the inactive element under 



413 



