SYNIUKSIS OF ORCi.WIC COMPOUNDS HV IONIZING RADIAIION 



the absorbed dose, the ferrous sulphate-sulphuric acid system was again 

 used in llu- cell placed in exactly the same position. The same system of 

 aeration was used. In this case the absorbed dose rate 1 -5 x 10^^ eV/ml./min 

 was rather less than had been anticipated. 



Analytical Techniques 



The detection of urea was found to be far from a simple matter l)ecause it 

 was complicated always by the presence of the more reactive ?«-])henyl- 

 enediamine. The method of Fosse using xanthydrol, which was detailed by 

 Loiseleur was at first used. This reagent is not specific for urea although 

 it does form a well-defined dixanthylurea derivatives^ Further, the reaction 

 was found to be erratic and even failed, \vhen used as recommended, to react 



100 



Wave numbers 



Figure 2. Infra-red spectra of dixanthylurea and unknown derivativ'e — A, unknown — B, 



urea derivative 



with rather large amounts of added urea. For example, 25 mg urea dissolved 

 in 10 ml. ethanol and 20 ml. glacial acedc acid failed to give the derivative 

 after standing for several days. In another case, 100 mg of urea produced 

 the derivative only after standing for twenty-four hours during which time 

 the mixture was shaken vigorously for several hours. On the other hand, 

 5 mg urea dissolved in 5 ml. water and 20 ml. glacial acetic acid gave the 

 derivative almost immediately following the addition of the xanthydrol. 



In the early stages of these experiments, what was thought to be the 

 derivative, dixanthylurea, obtained from the solution after irradiation, was 

 shown to be idendcal with a crystalline deposit recovered from a control test 

 with non-irradiated solution treated in the same way. This substance, as 

 yet unidentified, appeared regularly in both the irradiated and non-irradi- 

 ated solutions after standing for several days. The elemental analysis and 

 infra-spectra (shown in Figure 2), showed clearly that the substance was not 

 the same as the derivative obtained in the same way with a pure urea. 



112 



