A simple and rapid method to determine hexeneuronic acid groups in chemical pulps

This paper describes a neu procedure to determine hexeneuronic acid groups (HexA) in kraft pulp. The method is based on the highly selective hydrolysi s of HexA from a pulp sample in a mercuric chloride-sodium acetate solution . By choosing the appropriate hydrolysis conditions (the concentration of t he hydrolysis agent and the composition of the hydrolysis solution) and tem perature, not only ran a complete hydrolysis of HexA from pulps he achieved within 30 min, bur also the amount of HexA can he directly determined by U V spectrophotometry from the resulting solution. By using a dual-wavelength spectroscopic technique (at 260 and 290 nm), the spectral interference fro m the leached lignin in the resulting solution can be eliminated The presen t method is very simple and rapid and only a very small sample si;e is requ ired for analysis.