Determination of Hexenuronic Acids

The following gives a brief compilation of procedures to determine hexenuronic acids in cellulosic pulp samples. The common methods are based on hydrolysis of HexA moieties from pulp, either enzymatically or chemically, with subsequent quantification of the hydrolysis products either directly or after chemical conversion into UV active compounds. A comparison of these three methods is given by Tenkanen et al. [136]. For comparison rather than exact determination of HexA, e.g., during bleaching stages, the diffuse reflection UV VIS method can be applied [137]. A photoacoustic FTIR procedure based on chemometric analysis has been described as well [138]. In Table 3, the available methods to analyze HexA moieties in cellulosic material are summarized. 

Resonance Raman Direct detection of double bond Resonance Raman [143,144] 

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Table 3 Methods for the determination of hexenuronic acids in cellulose...

M Ragnar. A Novel Spectrophotometric Tool for Bleaching Smdies and Determination of Hexenuronic Acid Removal. Nordic Pulp Paper Res. J. 16 68-71, 2001. 

M Tenkanen, G Gellerstedt, T Vuorinen, A Teleman, M Perttula, J Li, J Buchert. Determination of Hexenuronic Acid in Softwood Kraft Pulps by Three Different Methods. J Pulp Pap Sci 25 306-311, 1999. 

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