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    This method describes a procedure to determine hexeneuronic acid groups (HexA) in chemical pulps. HexA affects the kappa number determination by reaction with permanganate, and can react with certain bleaching chemicals, e.g. chlorine dioxide and ozone, but not with some others such as oxygen and peroxide. The method is based on the highly selective hydrolysis of HexA from a pulp sample in a mercuric chloridesodium acetate solution. Complete hydrolysis of HexA from pulps is achieved within 30 minutes by choosing the appropriate hydrolysis conditions (the concentration of the hydrolysis agent and the composition of the hydrolysis solution) and temperature. The amount of HexA is directly determined by UV spectrophotometry from the resulting hydrolysis solution (1). A dual-wavelength spectroscopic technique (at 260 and 290 nm) is used to eliminate the spectral interference from the leached lignin in the resulting solution.

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    Zhu, Junyong; Chai, X.S. 2007. Hexeneuronic acid content of chemical pulp. TAPPI test method ; no. T282pm-07. Atlanta, GA : TAPPI, c2007: 4 pages


    Permanganates, peroxides, oxygen, ozone, pulping, chemical reactions, wood-pulp, bleaching, hydrolysis, chlorine dioxide, mercuric chloride, sodium acetate, chemical pulping, alkaline pulping, hexeneuronic acid

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