Discriminative analysis of Eucalyptus camaldulensis grown from seeds of various origins based on lignin components measured by pyrolysis-gas chromatography

Pyrolysis-gas chromatography (Py-GC) using a vertical microfurnace pyrolyzer combined with the principal component analysis (PCA) was applied to the discriminative analysis of Eucalyptus camaldulensis trees grown at the same field from the seeds of different origins. On the pyrograms of the Eucalyptus samples obtained at 450 °C, many characteristic peaks derived from syringyl (S) and guaiacyl (G) units of lignin were reproducibly observed along with those derived from cellulose and hemicellulose. First, the discriminative analysis among the Eucalyptus trees was attempted on the basis of the S/G ratio calculated from the relative peak intensities of the pyrolyzates characteristic to lignin. However, it was difficult to make unequivocal specification for the origins of the seeds by the observed S/G ratio alone. Then, the PCA was applied to discriminate Eucalyptus tree samples based on the molar yields of the peaks specifically derived from lignin observed by Py-GC. As a result, the origin of Eucalyptus trees was successfully discriminated even grown at the same field.