Analytical pyrolysis as a direct method to determine the lignin content in wood Part 3. Evaluation of species-specific and tissue-specific differences in softwood lignin composition using principal component analysis

Both the genetics and the environment determine the chemical composition of wood. To assess the chemical composition analytical pyrolysis is being increasingly used. Each single pyrogram is a fingerprint of the chemical composition that should reflect tissue, species, and site related information although hidden in an amount of data. Principal component analysis was applied to evaluate the pyrolysis results with respect to differences in lignin composition using G- and H-lignin-derived peaks from the pyrograms, The three species: pine, spruce and larch were separated in the first principal scores plot and the corresponding loadings plot revealed that it is vanillin (G 9) and G-C=C=C (G 11) on one hand and isoeugenol (G 8) and dihydroconiferyl alcohol (G 19) on the other hand that separate spruce and larch from pine. Beside others G 9 plus G I I and G 8 plus G 19 separate spruce form larch as well as Vaquey pine from Blagon pine. In addition an investigation of the different tissues - normal wood and reaction wood - and the discussion of these results together with the loadings helped to reveal the differences in lignin composition between the species, tissues, and two sites. It was shown that analytical pyrolysis combined with principal component analysis could be useful for the identification of species and their origin. (C) 2008 Elsevier B.V. All rights reserved.