用双波长可见光谱法快速测定半纤维素提取液中糖的含量

传统的Douglas比色法(间苯三酚-冰醋酸显色法)只能测定水溶性聚戊糖或戊糖,该研究对上述方法进行了改进,通过采用双波长技术实现对总糖和戊糖、己糖含量的同时测定。研究发现,425 nm是戊糖和己糖的等摩尔吸收波长,553 nm是戊糖的特征吸收波长,以上述二波长为基础大大简化了双波长法的计算公式。半纤维素提取液中干扰物质的光谱结果显示,提取液中的木素和葡萄糖醛酸对戊糖和己糖的测定结果都没有显著干扰。结果表明,该方法测定总糖和戊糖、己糖的含量都具有较高的精度和准确性,回收率为97.4%~101.9%。该方法简单、快速,非常适用于阔叶木和禾本科植物半纤维素提取液中混合糖含量的同时测定。

Rapid Determination of Sugars in Hemiceilulose Extraction Liquor by Dual-Wavelength Spectrophotometry

The traditional Douglas colorimetric method (phloroglucinol - glacial acetic acid colorimetry) could only be used to measure all forms of five-carbon sugars, including mono-, oligo- and poly- saccharides. Relative improvement is done on this method to achieve simultaneous deter ruination of pentosan, hexosan and their monosaccharides, by the dual-wavelength method.Results indicate that 425 nm is the equal molar absorption wavelength of pentose and hexose, while 553 nm is the maximum ab-sorption wavelength of pentoses. So the calculating formtda has been greatly simplified based on the absorbance at 425 and 553 nm. The research results of interfering substances in the extraction liquor show that the lignin and glucuronic acid has no signifi-cant influence on the deter ruination of pentoses or hexoses. It is concluded that this improved method has high precision and ac-curacy, and its recovery range is from 97. 4% to 101.9%. Therefore, as a simple and rapid method, it is quite appropriate for measuring mixed sugars of pentoses and hexoses in the extraction liquor from hardwood or gra minaceous plant.