So, what you can do, are:
1). Extracting with n-heptane (or n-hexane, or n-penetane), cyclohexane and diethyl ether, followed by GC of the organic extracts.
Theoretically, GC chromatograms are identical but with slightly different quantitative appearance, due to the slightly different partition coefficients in the above solvents.
Indicatively, lipophilic compounds with polar groups hate to be mixed in cyclohexane but prefer diethyl ether.
2). A series of normal phase HPLC experiments, in mixtures of n-hexane/ethyl acetate and cyclohexane/ethyl acetate at various volume ratios, as eluants and using both UV and refractive index detectors. Only, aromatic and unsaturated compounds are detected by UV detector (say, at 254 nm). While, both aromatic and aliphatic compounds can be detected by refractive index detector (but with higher detection limits).
3). A series of reverse HPLC experiments, in (say) acetonitrile/water at various volume ratios, using both UV and refractive index detectors.
4). Matching the chromatograms peaks with the ones of known compounds form the literature, EPA standards, etc.
5). Using more advanced techniques, such as GC/MS and LC/MS, for the chemical structure identification.