Samples of 30% tributyl phosphate (TBP)-n-dodecane-HNO3 undergoing gamma radiolysis with and without solvent cleanup have been examined by GLC and IR spectrometry. In order to assess the rate of buildup of various radiolytic species in the solvent, their relative hydrophobicities with respect to alkaline wash have been determined. The differences in the Pu extraction and retention behaviors of the two solvent systems with increasing dose are explained in terms of the formation of derivatives of nitroparaffins and high molecular weight organophosphates.