Radiolysis of uracil in the presence of nitrous oxide and nitrate ion

Aqueous solutions of uracil (U) were irradiated with Co-60 γ-rays in the presence of electron scavengers, e.g. nitrous oxide and nitrate. Analysis of the products was carried out by means of paper chromatography. In N2O saturated solution, the degradation of uracil has been ascribed to the intermediate formation of a hydroxyl adduct which it has been argued leads to products through an electron transfer process, and G(-U) was found to be equivalent to 0.5 Gsub(R) where R comprises H, esub(aq)-and OH. The observed results have been compared with those reported earlier and the apparent anomalies have been rationalised in terms of a dose rate effect. NO3- ion has, however, been found to behave somewhat differently as an electron scavenger. The concentration of NO3- was found to be a decisive factor in determining the course of radiolysis. Thus G(-U) is equivalent to approx. 0.5 Gsub(R) at low or zero nitrate concentration, approx. 0.5 Gsub(OH) over the range (0.5 to 3) x 10-3 M and approx. Gsub(OH) at higher concentrations. (author)