Structural differences in lignin between Eucalyptus clones determined by analytical pyrolysis-gas chromatography/mass spectrometry

In this study, a large number of wood samples from several species of Eucalyptus, including E. grandis, E. urophylla, E. globulus, E. dunnii, E. camaldulensis and their crossing were characterized by pyrolysis-GC/MS method. All the measurements were done directly from the Eucalypus wood samples. S/G ratios were calculated for all guaiacyl and syringyl lignin pyrolysis derivatives. The results were compared with the S/G ratios measured by nitrobenzene oxidation method. S/G ratios obtained by the two methods were close to each other. However, no linear correlation between the methods was found. Overall variation in lignin structure between different Eucalyptus hybrids was minor. However, due to the sensitivity of the pyrolysis-GC/MS method, it was possible to detect differences in lignin structures that correlate to the species in the hybrids.