1H NMR光谱法同时测定羟丙基壳聚糖的摩尔取代度及其分布分数、乙酰化度,Carbohydrate Polymers

在13 C NMR 和1 H- 13 C HSQC 的帮助下，我们通过优化样品制备和测量方法，开发了一种新的1 H NMR 测定羟丙基壳聚糖 (HPCS) 中的取代位点和取代度。我们发现 HOD 峰的化学位移随着 DCl 浓度的增加线性增加，但随着测量温度的升高而下降。根据回归线，可以通过改变 DCl 浓度将 HOD 峰移动到不干扰其他峰的所需位置。发现并阐明了其他 DCl 响应峰。因此，取代分数 (NH 2-取代和OH-取代）和乙酰化程度被很好地区别和确定。得到的总取代度（MS）与元素分析和现有核磁共振方法基本一致。这种结构分析可扩展到其他含氨基的糖类。的1种1 H NMR方法可广泛应用在可溶于酸的多糖及其衍生物一起使用。

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Under the assistance of 13C NMR and 1H-13C HSQC, we develop a novel 1H NMR assay for the substitution sites and degrees in hydroxypropyl chitosan (HPCS) by optimizing sample preparation and measurement method. We find that the chemical shift of HOD peak increases linearly with the increase of DCl concentration but declines with the rise of measurement temperature. According to the regression line, the HOD peak could be moved to a desired position of non-interference with other peaks by changing DCl concentration. Other DCl-responsive peaks are found and elucidated. Accordingly, the substitution fraction (NH2-substitution and OH-substitution) and the degree of acetylation are well discriminated and determined. The total degree of substitution (MS) obtained is basically consistent with those of elemental analysis and the existing NMR methods. This structural analysis is extendable to other amino-containing saccharides. The 1H NMR method could be used widely in acid-soluble polysaccharides and their derivatives.