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In our previous studies, a method of quantitative analysis of lignin structure by IR spectroscopy with direct use of wood meal was developed which can be apply to a wide range of wood species. Lignin structure deposition in different fractions in the same wood sample also has characteristic diversity and differences. In this study, quantitative analysis of lignin structure by IR spectroscopy was used to determine whether it can be applied to different fractions in the same wood sample. Finely milled beech wood was fractionated by stepwise extraction using aqueous dioxane and followed by subsequent dimethyl sulfoxide (DMSO)/LiCl solvents with increasing LiCl concentrations. The results showed that fractions of the peak area ratio of log(1595/1509) fit a linear relationship with different wood species very well. Therefore, log(1595/1509) could be used not only with different wood species but also with different fractions from the same wood. For 1509/1460, log(1275/1220), 1130/1030 and 835/(835+815), different fractions deviated from the original relationship obtained from different wood species. [ABSTRACT FROM PUBLISHER]

The composition and absolute amount of neutral sugars were determined for 48 hardwood species (including 17 hardwoods of generaAcacia, 14 hardwoods of generaEucalyptus, and 17 hardwoods of other genera) and 14 softwood species by alditol-acetate method, and their relationships to the syringyl ratio (syringyl/(syringyl+guaiacyl)) of lignin, which was determined by nitrobenzene oxidation, was investigated. In the hardwood species, an increase in the syringy ratio of lignin correlated with a tendency toward increased xylose/glucose, rhamnose/glucose, and arabinose/glucose ratios. However, the absolute amount of glucose in hardwood was maintained in a small range (0.4–0.5 g in 1 g sample), independent of changes in the syringyl ratio. In the softwood species, with increasing lignin content, the mannose/glucose ratio decreased, but the absolute amount of glucose remained almost constant. In both hardwood and softwood species, a strong correlation was suggested between lignin, indicated by higher syringy ratio, and hemicellulose, indicated by higher xylan/mannan ratio. [ABSTRACT FROM AUTHOR]