豆类中非淀粉多糖组分糖醛酸的分光光度法测定

Spectrophotometric Determination of Uronic Acid of Non-Starch Polysaccharides in Bean Products

糖醛酸为非淀粉多糖中的组分之一 ,浓H2SO4和糖醛酸在70℃时反应 ,可以生成5_甲酰基_2呋喃甲酸 ,该化合物可以用选择性极强的3,5_二甲基酚显色 ,并在450nm波长处产生最大吸收 ;采用双波长分光光度法以消除样品中木质素和中性糖等化合物的干扰 ;测定波长为450nm ,参比波长为中性糖吸收最大的波长400nm ;检出限为2mg·L -1;利用本法测定了几种豆类中非淀粉多糖组分糖醛酸的含量 ,精密度 (以RSD表示 )范围为0.06%～0.14 % ,回收率为96.8 %～103.9 %。

The proposed method was based on the reaction of the chromogenic reagent,3,5-dimethylphenol with5-formyl-2-furancarboxlic acid which was produced when uronic acid in concentrated H 2 SO 4 was heatˉed at70℃.Dual-wavelength spectrophotometrywas used to eliminate the interference fromlignin and neuˉtral sugar products.The maximumabsorbing wavelength of the colored compound,450nmwas used as the analytical wavelength,whereas the maximum absorbing wavelength of neutral sugar,400nm was used as the reference wavelength.The detection limitwas2mg·L -1 .The precision(expressed in RSD)of the deˉtermination of uronic acid in several bean products was0.06%～0.14%and the recovery was96.8%～103.9%.