286 



PRASEODYMIUM 



Praseodymium 142 (19.2 hr) 



Cat. No. Sp. Act. Form 



Pr- 142-1 550 mc/g PraOa 



Beta 0.66, 2.23 Gamma 0.134-1.59 



Cost Chem. Cont. Radiochem. Cont. 



$13/40 mc — — 



Intake Levels. Praseodymium is a rare earth and has not been of 

 biological importance except that Pr^^^ is produced in the fission process 

 and its metabolism in living systems is therefore of interest. 



Radioassay. Preparation Pr-142-I has the advantage of lower cost and 

 more energetic and easily measured radiation, but the disadvantage of a 

 lower specific activity and, for some studies, too short a half-life. Rou- 

 tine beta or gamma counting can be employed for Pr^*^, but only beta 

 methods for Pr^^^. 



Chemistry. Methods are not available for chemical estimation of this 

 element in biological material. Presumably, wet- or dry-ashing methods 

 may be used. Separation from other rare earths may be accomplished by 

 dry oxidation with NaNOs and extraction with buffered acetic acid which 

 leaves the praseodymium behind as an insoluble residue (Pr-1). 



Pr-l. Coryell, Charles D., and Nathan Sugarman: "Radiochemical Studies: The 

 Fission Products," Books 1-3, National Nuclear Energy Series, McGraw-Hill 

 Book Company, Inc., New York, 1951. 



