Separation of conservation agents, including polyethylene glycol (PEG), from the wood of the original artifact, has been performed by double-shot hexamethyldisilane (HMDS)-pyrolysis-GC-MS . One advantage of THM-GC-MS is insensitivity to PEG treatment, as PEG is broken down by tetramethylammonium hydroxide (TMAH) to early eluting volatile components in the solvent vent part of the GC-MS method and thus is not present in the resulting gas chromatograms.