CADMIUM 217 



Cadmium 115 (53 hr) Beta 0.46, 1.1 Gamma 0.52, 0.34 



Cat. No. Sp. Act. Form Cost Chem. Cont. Radiochem. Cont. 



Cd-nS-I-l 20mc/g Metal .$12/20 mc — 0.3 mc Cd'"*"* (43 days) 



20 mc In' '5"' (4.5 hr) 



Mica \V. Int. C. Scint. C. Rf/mc 50% Self -abs. 



1.9 X 10-^ 1.4 X 10-^ 3.2 X 10-3 4 100 (calc.) 



Cadmium 115m (43 days) Beta 1.67 Gamma 0.5 



Cat. No. Sp. Act. Form Cost Chem. Cont. Radiochem. Cont. 



Cd-1 15-1-2 1 mc/g Metal $33/mc — 22 mc Cd'i^ (53 hr) 



Cd'»9 

 Cd-115-P 5-20 mc/g Nitrate $33/mc — — 



Mica W. Int. C. Scint. C. Rf/mc 50 % Self-abs. 



2.5 X \0 * 3.8 X 10-4 4 5 x 10-^ 3 156 (calc.) 



Intake Levels. Foods contain about 1 ppm; crop plants range from 

 0.02 to 2 ppm. About 15 ppm in food produces mild poisoning, and 

 about 135 ppm in the diet was toxic for rats. 



Radioassay. Preparation Cd-115-P is probably the best for general 

 use, since the others contain appreciable radiocontaminants. Routine 

 beta or gamma counting is satisfactory. 



Chemistry. Methods have been described for determination of as 

 little as 0.4 ng cadmium in biological material (Cd-1, Cd-2). In general, 

 the element is separated from the wet-ash matrix by extraction with 

 dithizone in chloroform in preparation for spectrographic, polarographic, 

 or colorimetric evaluation. 



Typical Methods. Following is a method for ashing used in the chem- 

 ical determination (Cd-1) : The sample, up to 20 g of tissue, is wet-ashed 

 with a H2SO4-HNO3 mixture, and the digest evaporated to fumes of SO3; 

 any char is destroyed by repeated additions of nitric and perchloric acids. 

 The ash solution is mixed with ammonium citrate and extracted with 

 dithizone in chloroform. 



Cd-1. Cholak, Jacob, and Donald M. Hubbard: Determination of Cadmium in 

 Biological Material, Ind. Eng. Chem. Anal. Ed., 16 : 333-336 (1944). 



Cd-2. Shirley, Ray L., Erwin J. Benne, and E. J. Miller: Cadmium in Biological 

 Materials and Foods, Anal. Chem., 21 : 300-303 (1949). 



