红外光谱法测定N-酰化壳聚糖的取代度

以从完全脱乙酰壳聚糖通过均相N-乙酰化法制备的不同脱乙酰度(D.D.)壳聚糖为红外标准样品,通过评价1655,1560,1380和1320 cm^-1 4条可能的分析谱带,3430, 2920,2880,1425,1155,1070,1030和895 cm^-18条可能的参比谱带以及2种基线法组成的48种组合, 选出了适合于壳聚糖脱乙酰度红外测定的最佳组合为A₁₅₆₀ / A₂₉₂₀, A₁₅₆₀ / A₂₈₈₀和A₁₆₅₅ / A₃₄₃₀(推荐使用A₁₅₆₀ / A₂₈₈₀).测量1560和1655 cm^-1谱带的吸光度以第2种基线作法(即此两峰相邻的峰谷连线)为佳.D.D.的测量范围几乎覆盖了全程即1%~100%.后两种最佳组合的工作曲线还可适用于N-丙酰化、N-丁酰化和N-己酰化等N-烷酰化壳聚糖的取代度测定.     

Determination of degree of substitution for N-acylated chitosan using IR spectra

Chitosans with various degrees of deacetylation (D.D.), which were used as standard sample for FTIR determination, were prepared from completely deacetylated chitosan by homogeneous N-acetylation reaction. By combining four probable probe bands, i.e. 1655, 1560, 1380 and 1320 cm-1, eight probable reference bands, i.e. 3430, 2920, 2880, 1425, 1155, 1070, 1030 and 895 cm-1 and two baseline methods, the most suitable ratios Aprobe band/Aeterence band from IR spectra to determine the degree of acetylation of chitosan were evaluated from 48 combinations to be A1560/A2880, A1560/A2920 and A1655/A3430(A1560/A2880 is mostly recommended). The second baseline method, i.e. linking between adjacent two valleys, was better for measuring the absorbances of 1560 and 1655 cm-1 bands. The determination range of the D.D. (1%-100%) covered almost the whole range. The standard curves with A1560/A2880 and A1655/A3430 were also suitable for the determination of degree of substitution of other N-acylated chitosan, such as N-pr     

鱿鱼顶骨β-甲壳素的化学反应活性及其与α-甲壳素的比较

研究了由鱿鱼顶骨提取的β－甲壳素和β－壳聚糖分别对O－丙酰化（非均相反应）和N－乙酰化（均相反应）的反应活性，并与α－甲壳素／壳聚糖进行了比较，结果表明，β－甲壳素的反应活性比α－甲壳素差，β－甲壳素经水磨微纤化后，丙酰化反应活性虽然显著提高，但仍低于α－甲壳素，本文用偏光显微镜和电子显微镜首次观察到微纤化的β－甲壳素中可以分辨出4个层次的纤维状结构，它们分别是微纤束，微纤，细微纤和原纤，直径分别为10^1,10^0,10^-1,10^-2μm数量级，由于暴露出各次微纤上更多的自由羟基，从而微纤化提高了反应活性。