Pyrolysis gas-chromatography mass-spectrometry (Py-GC/MS) to identify compression wood in Pinus radiata saplings

The potential of pyrolysis followed by gaschromatography and mass-spectrometry (Py-GC/MS) was investigated for identifying compression wood (CW) in saplings of radiata pine (Pinus radiata) by examining samples of CW and opposite wood (OW). Phenolic compounds and anhydrosugars were identified among the pyrolysis products that provided information about the cell-wall polymers. Sample preparation, such as coarse-milling, fine-milling, and fine-milling followed by calcium-chloride treatment was also investigated. Fine-milling typically decreased the total yield of phenolic compounds compared with coarse-milling. Fine-milling followed by calcium-chloride washing significantly increased the proportions of pyrolysis products from polysaccharides, specifically from (1→4)-β-D-galactans that were of interest in distinguishing CW from OW. Six pyrolysis products were identified that were unique to the CW samples examined, including derivatives of (1→4)-β-D-galactans and H-units of lignin. Other pyrolysis products were identified that had significantly different proportions between the two wood types, and sometimes among samples of the same wood type.