Phenolic acids as indicators of wood tannins

Liquid chromatographic analysis is used to identify oak tannin fractions by their phenolics, i.e. gallic and ellagic acids, and acacia tannins by vanillic acid and syringaldehyde. Chestnut tannins also contained gallic acid while their chromatographic profile differed otherwise from the oak pattern. Spruce and fir tannin fractions did not contain identifiable major phenolics and their tannin concentrations were also an order of magnitude less than the above-mentioned woods. Whereas the identified phenolics accounted for only a part of the total tannins, there was a correlation with the general tannin content of the wood expressed as tannic acid equivalents. Thus, the method can probably be used for taxonomic purposes and for a specific detection of hard wood exposure in carpentry shops and in other wood working trades. (C) 1997 Elsevier Science B.V.