熱分解ガスクロマトグラフィーによるリグニンの構造解析（第３報） 広葉樹材のアルカリ性ニトロベンゼン酸化との比較

Abstract

In order to study the effectiveness of pyrolysis-gas chromatography (Py-GC) on the structural analysis of lignin, wood meals of 13 Japanese hardwood species were subjected to Py-GC and the results were compared with those of nitrobenzene oxidation. Thirteen compounds with guaiacyl nucleus were identified as pyrolysis products along with their syringyl analogues by comparing their retention times and mass spectra with those of authentic compounds. Quantitative analyses were performed by using the calibration factors which determined by quantitative gas chromatographic analysis of authentic compounds. Total yields of monomeric pyrolysis products were between 12.2 and 26.1% of Klason lignin and were found to be different among wood species. Total yields of vanillin (V) and syringaldehyde (S) obtained by nitrobenzene oxidation were between 31.7 and 43.9% of Klason lignin and were almost twice as large as those of the pyrolysis products. The ratios of syringyl type products to guaiacyl type products were in good agreement with the S/V molar ratios obtained by nitrobenzene oxidation. Accordingly, Py-GC is expected to be a time saving and convenient routine method for characterizing hardwood lignin because the method requires only small amount of samples and no preliminary chemical processing. However, accumulation of analyses data on the yields of pyrolysis monomers is still insufficient. Further studies using other hardwood species are considered to be necessary.