RADIOACTIVATION ANALYSIS 



423 



gold thiosulfate. At sacrifit-e, tissue samples were wet-ashed and irra- 

 diated in the pile. At the same time, a standard solution containing 

 10 Mg Au as the chloride was irradiated wdth the same flux as received by 

 the ashed tissue samples. Carrier gold was added to each sample and 

 was then separated along with the induced Au>''« by precipitating as the 

 metal and then electroplating on platinum planchets for radioassay of 

 Aui^^ Decay curves for each sample indicated that excellent separation 

 of Au'«« had been obtained. Some typical values are presented in 

 Table 10-5. 



Table 10-5. Distribution of Gold as Determined by Radioactivation 



Analysis in Mouse Tissues at 30 Days after Intravenous 



Administration of 10 fxo of Stable Gold 



Liver 



Adrenals 



Lymph nodes 



Bone 



Brain 



Muscle 



Plasma 



[From Cornelius Tobias and Rayburn W. Dunn, Analysis of Microcomposition of 

 Biological Tissue by Means of Induced Radioactivity, Science, 109: 109-113 (1949).] 



Tobias and Dunn (21) also reported the levels of induced radioactivity 

 in tissue ash after exposure to thermal neutrons. From radioactivation 

 of 10 ml of blood from a leukemic patient, it was found that the^ total 

 white cells, red cells, and plasma of the body contained 14.3, 10.5, and 

 18.5 Mg, respectively, of naturally occurring Au'". 



Cobalt. About 1-g portions of crude biological material were placed 

 in quartz ampoules for irradiation (7) ; miUigram amounts of cobalt metal 

 were used as standards. A weighed portion of the irradiated sample was 

 wet-ashed with H.2SO4 and HNO3. A known amount of cobalt carrier 

 and copper, iron, nickel, zinc, strontium, and sodium holdback carriers 

 were added. Strontium was separated as the sulfate, copper as the 

 sulfide, and iron as the hydroxide. The cobalt, nickel, and zinc were 

 precipitated as the basic sulfides, and cobalt separated from nickel and 

 zinc as a precipitate of potassium cobaltinitrite. The latter precipitate 

 was washed, dried, weighed, mounted, and counted with a scintillation 



counter. , r 



Strontium. For determination of strontium, about 0.2-g samples 01 



animal tissue were placed in small (luartz tubes for irradiation; milligram 



