Distribution of Guaiacyl and Syringyl Lignins

Distribution of guaiacyl and syringyl lignin in various morphological regions of white birch (Betula papyrifera) [78]... 

By combining the bromination-EDXA technique with ultraviolet (UV) microscopy, it is possible to determine not only the distribution of lignin but also the distribution of guaiacyl and syringyl residues in various morphological regions (Saka et al. 1988, Saka and Goring 1988). 

Table 4 4 2 shows the experimental data for Br-Ka X-ray counts (I), UV absorbance (A) and the distribution of lignin for different morphological regions of white birch (Betula papyrifera) wood Because of the limited resolution of UV microscopy, the UV absorbance of the S, S3 layers and the middle lamella between cell corners (ML) cannot be measured Instead, the guaiacyl/syringyl ratios are assumed to be the same as in the S2 layer and the cell corner middle lamella (CC), respectively... 

Musha Y, Goring DAI (1975) Distribution of syringyl and guaiacyl moieties in hardwoods as indicated by ultraviolet microscopy. Wood Sci Technol 9 45-58 Parham RA (1974) Distribution of lignin in kraft pulp as determined by electron microscopy. Wood Sci Technol 6 305-315... 

Research on the chemical nature of hardwood xylem has revealed that the walls of fibers and ray cells contain lignin of one type, syringyl, while vessel walls together with the surrounding middle lamella are rich in lignin of a second type, guaiacyl, which is the same type found in softwood xylem (9, 10). This basic chemical difference between hardwoods and softwoods could, in some instances, potentially influence phenomena that depend on the chemical nature or reactivity of wood tissue at the cellular level. Further details on the nature and distribution of wood chemical constituents are found in Chapter 2. 

Woods B and Calnan CD (1976) Toxic woods. British Journal of Dermatology, 95 (suppl 13) Wu J, Fukazawa K and Ohtani J (1992) Distribution of syringyl and guaiacyl lignins in hardwoods in relation to habitat and porosity form in wood. Flolirforschung, 46 181-5 Wu Q (1989) An investigation of some problems in drying of Tasmanian eucalypt timbers. 

Fig. 8.1 The schematic distribution of the lignin types (guaiacyl, G, syringyl, S, and p-hydroxyphenyl hgnin, H) in the major classes plants [7, 8, 10-12]...

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