Effects of γ-Irradiation on Sodium Sulphacetamide

The effects of γ-irradiation on sodium sulphacetamide in aqueous solutions and in the solid state have been studied. Pulse radiolysis and steady-state experiments demonstrate that hydrated electrons $({\rm e}_{{\rm aq}}^{-})$ and hydroxyl radicals (OH) are mainly responsible for the degradation between $10^{-4}-1.2\ M$ solute concentrations. The reaction with ${\rm e}_{{\rm aq}}^{-}$ yields sulphanilic acid and an additional unidentified product. Hydroxyl radicals give two products which have tentatively been identified as monomeric and dimeric phenolic derivatives of sulphacetamide. Suitable ${\rm e}_{{\rm aq}}^{-}$ and OH scavengers selectively remove these products. G(-sulphacetamide) is a maximum of 4.8 in aqueous solution and < 0.01 for the solid. The implications of the results in the radiation sterilization of sulphacetamide formulations is discussed.