Abstract An improved method for the separation of the components of plastic explosives is described with the goal of stable isotope ratio analysis of each isolated component. The binder and plasticizer of a plastic explosive were extracted into cyclohexane, leaving the explosive components and other insoluble material. The plasticizers, oils, and additives were next extracted from the dried cyclohexane-soluble fraction into acetone, leaving the polymeric binder. Plasticizers, oils, and additives were identified by GC–MS and individual plasticizers, oils, dyes, and antioxidants were isolated by GC and/or flash chromatography free of interfering materials. The explosive components were extracted from the cyclohexane-insoluble fraction with acetone, and then quantitatively analyzed for individual explosive compounds via HPLC-UV/Vis spectroscopy. Individual explosive compounds were isolated via preparative HPLC. The separation process was validated by gravimetric, HPLC-UV/Vis, EA, GC–MS, TC/EA, and FTIR results consistent with the expected formulation of the plastic explosives. The isolated components were analyzed for component-specific stable isotope ratios. Control mixtures of previously characterized components of two common plastic explosive formulations were also separated and analyzed. These isolated components retained the isotope ratios prior to mixture, demonstrating the robustness and reliability of the technique. Two example C-4 explosives from different sources, with indistinguishable chemical composition and raw explosive 13 C/ 12 C and 15 N/ 14 N isotope ratios, were extracted and analyzed. The resultant binder and plasticizer 2 H/ 1 H and 13 C/ 12 C results were used to discriminate between the two C-4 samples that were otherwise apparently identical.