Analytical Pyrolysis of Hardwood and Softwood Lignins and Its use in Lignin-Type Determination of Hardwood Vessel Elements

Abstract

Abstract Pyrolysis-gas chromatography-mass spectrometry was performed on milled wood lignins (MWLs) and wood samples. Among the major pyrolysis products identified from loblolly pine lignin were guaiacol, 4-methylguaiacol, 4-vinylguaiacol, vanillin, coniferal-dehyde, and coniferyl alcohol. White oak lignin pyrolysis products also included guaiacol, 4-methylguaiacol, and vanillin and additionally 2,6-dimethoxyphenol, 4-methyl-2,6-dimethoxyphenol, syringaldehyde, and sinapaldehyde. By identification of these pyrolysis products from either wood or MWL it is possible to classify lignins as either guaiacyl-type or syringyl/guaiacyl-type. Pyrolysis of isolated vessel elements from white oak, white birch, and American elm indicated that vessel lignin is of the syringyl/ guaiacyl-type.