Concerning Determination of Lignin in Bark

Wood and wood bark, from the botanical viewpoint, are firmly bound polymer natural substances. Therefore, their chemistry is commonly regarded jointly, although distinctions are essential, especially in organic chemistry and analytical aspects, which determines the wood and bark components’ composition. The issue of lignin definition in bark and its quantitative determination is problematic and widely discussed. The lignin content in bark is higher than in wood. In the majority of analytical studies, lignin in bark is determined by the classical Klason method, hydrolyzing the analyzed material with 72 % H2SO4 at 20 oC. If, in the case of wood, the Klason method gives the really true lignin content in situ, then it is not so when analyzing bark, as the presence of diverse extractives influences the course of the analysis. The present study reflects the results obtained investigating the bark of tree species typical for Latvia