Gamma radiolysis of Purex solvent, 30% tri-n-butylphosphate-n-dodecane-HNO3 is observed to yield many undesirable metal complexing species. A method for identifying the gas-liquid chromatographic (GLC) signatures of high molecular weight organophosphates (HMPs) through a nitrogen- and phosphorous-selective detector is described. Fractionation of the radiolyzed solvent by vacuum distillation resulted in the enrichment of HMP species in the high boiling, viscous residue in the last fraction. This residue showed intense infrared signals characteristic of the presence of nitro, carbonyl, and phosphoryl groups, which implies the presence of multifunctional species. The study revealed a strong association among the components of radiolyzed solvent, which inhibits clean fractionation. Gas chromatography-mass spectrometry assay of the sample indicated that these HMPs consist of (NO2-C4H8)(C4H9O)(2)PO, (OH-C4H8O)(C4H9O)(2)PO, and (CH3-C4H8)(C4H9O)(2)PO species. The HMP-rich fraction exhibited very high plutonium-retention behavior, which Was substantially lowered by efficient uptake of HMPs upon alumina treatment. Thus, the present study correlates the GLC signatures of HMPs, especially those of nitrated species, formed by radiolysis of 30% tri-n-butylphosphate-n-dodecane-HNO3 and solvent quality deterioration with respect to Pu-retention behavior.