Gel permeation chromatographic study of the molecular weight distribution of tannins in the wood, bark and leaves of Eucalyptus spp.

The molecular weight distribution of tannins from the wood, bark and leaves of Eucalyptus camaldulensis, E. globulus and E. rudis from two different Spanish provenances has been studied by high performance gel permeation chromatography, using the compounds' acetylated derivatives. The MW distribution profiles showed important variability depending on the type of vegetal tissue, the species and, in some cases, on the geographical provenance of the samples. Bark was the vegetal tissue that yielded tannins with the highest molecular weight, followed by wood and leaves. Tannins from wood and bark of E. camaldulensis were of higher molecular size than those from E. globulus and E. rudis; those in the leaves of E. globulus and E. camaldulensis were similar in molecular size and larger than those in the leaves of E. rudis.