羧甲基木薯淀粉的取代方式研究

Investigation of Substituted Pattern of Carboxymethylation Cassava Starch

采用高效液相色谱(HPLC)和核磁共振波谱(1HNMR)分析了混水/有机介质中合成羧甲基木薯淀 粉的取代方式。发现HPLC是一种测定不同条件下合成的羧甲基木薯淀粉取代度(DS)的可靠方法。在测量 的范围内,未取代、一取代、二取代和三取代无水葡萄糖单元的摩尔分数分布和Spurlin模型非常吻合。用高 分辨率500MHz1HNMR分析了木薯淀粉羧甲基过程的取代度和反应顺序。依据淀粉和羧甲基淀粉(CMS) 的结构确定了各个峰位置。比较所得数据发现:依据HPLC计算的DSHPLC小于从500MHz1HNMR计算所得 的DS。无水葡萄糖单元中C2、C3和C6的羧甲基化反应顺序为C6>C2>C3。

High performance liquid chromatography ( HPLC) and proton nuclear magnetic resonance (H-1 NMR) were used to analyze the substitution pattern of carboxymethylation cassava starch etherificated in water-miscible organic media. Through HPLC analysis for different carboxymethyl cassava starches, it can be found that HPLC is a reliable technique to determine the degree of substitution (DS) of carboxymethylated cassava starch etherificated at different conditions. The mole fractions of unsubstituted, monosubstituted, disubstituted, and trisubstituted anhydroglucose units are in very good agreement with Spurlin model during the determined range. High resolution H-1 nuclear magnetic resonance ( NMR) of 500 MHz was used to analyze the degree of substitution and the reaction preference for carboxymethyl process. All peaks were assigned according to the structure of starch and carboxymethyl cassava starch ( CMS). Comparing the data it is found that all DS values calculated from HPLC, DSHPLC are lower than those calculated from the spectra of 1H NMR of 500 MHz, DSNMR. The etherificating reaction preference of C2, C3, and C6 among anhydroglucose is C6 > C2 > C3.