A new method for quantifying hexenuronic acid groups in chemical pulps, Journal of Pulp and Paper Science, March 2001, Vol. 27(3)

Z.-H. Jiang, A. Audet, J. Sullivan,

B. Van Lierop, R. Berry

This report documents the development of a simple, rapid and reproducible technique to quantify hexenuronic acid groups in pulps. In the proposed method, hexenuronic acid groups were hydrolyzed selectively by sulphuric acid to form 2-furoic acid and 5-formyl-2-furoic acid. The furoic acid products were then separated by anion-exchange chromatography, and quantified by suppressed conductivity detection. Suitable acid hydrolysis conditions (pH 0.75, 99°C, 3.0 h and 1.0(Em Dash)5.0% consistency) were identified through a kinetic study on pulps and on pure xylan enriched with hexenuronic acid groups. The method requires less than 4 h to complete with excellent reproducibility (relative standard deviation of 1.5%, five replicate analyses) and can be used to determine the hexenuronic acid content in all types of chemical pulps. The reliability of the technique was corroborated by capillary zone electrophoresis, GC-MS and 1(superscript)H NMR analyses.