Originally publisliod in Xatuic 13, 754 (lO^f)). 



18. RADIOACTIVE INDICATORS IN THE STUDY 

 OF PHOSPHORUS METABOLISM IN RATS 



O. Chievitz and G. Hevesy 

 From the institute of Theoretical Physi(!S, University of Copenhagen 



Receis'T progress in the production of radioactive isotopes by neutron 

 Ijombardment makes the radioactive isotope of phosphorus ?|P easily 

 accessible. This isotope, which has a half-life value of 15 days, can be 

 utilised as an indicator of inactive phosphorus in the same way that 

 1 he radioactive isotopes of lead, bismuth and so on wen^ formerly used 



4- 





E 3H 



C 



3 

 O 



Q. 



a I - 



O 



c 



+ 



o 



+ 



o 



o o 



o 





-| ' 1 ' — 



II 15 



Number of Days 



1^ 

 19 



23 



27 



Fig. 1 . On the first day 7.4 per cent of phosphorus was found in the 

 faeces and 5 per cent in the urine 



as indicators of these elements. If, for example, we add active ifP 

 to 1 mgm of inactive phosphorus in such quantity that the Geiger 

 counter registers 1000 impulses per minute, carry out with the phos- 

 phorus activated in this way any sort of chemical or biological reaction 

 and then find that the product obtained gives 1 impulse per minute, 

 we may conclude that 1/1000 mgm of the phosphorus originally intro- 

 duced is present in the product investigated. 



