Chemical Effects of Ionizing Radiations on Aqueous Solutions of Aldohexoses

The chemical changes which follow y-irradiation of aqueous D-mannose solutions in oxygen (1) and in vacuo (2) and D-glucose solutions in oxygen have been previously reported (3, 4). In the present paper, the general pattern of degradation of hexoses after irradiation in aqueous solution will be considered, and to this end the chemical changes after y-irradiation of aqueous D-glucose solutions in vacuo are described. By studying the chemical changes after irradiation of D-sorbitol solutions (5, 6), it was shown that the nature of the final products is considerably modified by the presence of oxygen, although the initial radicals formed are similar in oxygen and in vacuo. The present study on D-glucose solutions in vacuo, following the work on the corresponding oxygenated system (3), is an attempt to evaluate the influence of oxygen on the mechanism of degradation of aldohexoses. Two previous investigations are relevant to the present study. Grant and Ward (7) identified gluconic acid and 2-oxo-D-arabinoaldohexose (glucosone) in y-irradiated evacuated D-glucose solutions and observed the formation of an acidic polymer. Bothner-by and Balazs (8) irradiated air-equilibrated solutions of D-glucose to doses of 1 x 107 rads of X-rays and electrons. No products were identified, although the presence of several was demonstrated by paper chromatography. Both teams of investigators comment on the previously reported (1) characteristic maxima at 260 to 270 m/i in the ultraviolet absorption spectra of irradiated glucose solutions. In our study, paper chromatographic and radioactive tracer methods are used to identify and estimate reaction products, and from yield-dose curves, initial degradation processes have been identified.