Screening of juvenile Pinus radiata wood by means of Py-GC/MS for compression wood focussing on the ratios of p-hydroxyphenyl to guaiacyl units (H/G ratios)

Abstract

Abstract Analysis of thin slivers of juvenile (2-year-old) pine wood by pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS) was explored as a fast and high-throughput method to assess compression wood (CW) via the ratio of the p-hydroxyphenyl to guaiacyl units (H/G ratio). Various chemical parameters such as contents of lignin, galactose, and p-hydroxyphenyl (H) units have been related to the CW in the tissue. The H/G ratio was calculated from all identified H and G lignin-derived pyrolysis products. The H/G ratio ranged between 0.019 and 0.052 for normal wood (NW) and between 0.133 and 0.227 for CW. There was a weak correlation between CW H/G ratio and Klason lignin content (R2=0.4), but it was not correlated to the galactose content. Lignin- and carbohydrate-derived pyrolysis products were subjected to principal component (PC) analysis. The first two PCs discriminate the CW from the NW, accounting for about 41% of the total variance in the dataset. The model developed based on lignin-derived peaks explained 54% of the variance.