Chemical analysis of polysaccharides in plantation eucalypt woods and pulps

The polysaccharides in a series of Eucalyptus globulus and E. nitens woods, and E. globulus pulps, were analysed by high performance anion exchange chromatography with pulsed amperometric detection (HPAEC-PAD), following hydrolysis with sulfuric acid. The technique was evaluated as a small-scale method for characterising multiple samples of eucalypt woods. Acetyl groups and 4-O-methylglucuronic acids (MeGUAs) associated with the hemicellulose fraction were removed during acid hydrolysis and were determined separately. Acetyl and MeGUA results were combined with the hydrolysis results to enable calculation of cellulose and hemicelluloses contents for each sample. The cellulose contents to the wood samples varied over the range 41-50% (E. globulus) and 36-44% (E. nitens), although the range of total polysaccharide contents was similar for both woods. Analysis of the pulp polysaccharides after enzymic hydrolysis showed that the pulps contained hexenuronic acids. The analyses for cellulose and hemicellulose content showed satisfactory precision, and gave values similar to those associated with gravimetry determination of cellulose and hemicelluloses. The hydrolysis-HPAEC-PAD method for carbohydrates is proposed as a better alternative to gravimetric techniques for exploring the relationship between the chemical composition of plantation eucalypt woods and their pulp yields and papermaking properties.