Characterisation of wood extractives by pyrolysis gas chromatography mass spectrometry of quaternary ammonium hydroxide extracts

The aqueous tetramethylammonium hydroxide extracts of heartwoods of a range of conifer softwoods and various hardwoods were flash heated and analysed by gas chromatography. Unique profiles were obtained which were indicative of the species. Some of the extracted compounds were characteristic biomarkers and hence potentially valuable in chemotaxonomy investigations. In most cases, gymnosperm origin was indicated by the detection of guaiacyl-derived compounds and angiosperm origin was reflected by the presence of both guaiacyl- and syringyl-derived compounds. Profiles of the pyrolysed extracts were generally less complex and more specific than those obtained by thermally assisted hydrolysis and methylation gas chromatography reported previously. The effects of variations in pyrolysis temperature on the pyrolysis profiles were also studied. The origin of the extractives of two species was investigated by methylating methyl alcohol extracts to determine whether the extracted compounds were free or bound to lignocellulose. Pyrolysis of a tetraethylammonium hydroxide extract was used to determine the sites of pre-existing methylation in a major extractive.