不同重均相对分子质量和氨基含量壳聚糖的制备及测定

Preparation and determination of chitosans with different weight average molecular weights and free amino-group contents

目的 :制备出不同 -NH2 质量分数和不同重均相对分子质量的精细壳聚糖制品 ,利用激光散射仪测定在不同脱乙酰条件下所获得的壳聚糖重均相对分子质量 .方法 :利用反应温度为 14 0℃ ,反应时间为 1～ 4h和反应温度为 30℃ ,反应时间为 7d这两种不同方法 ,制备不同 -NH2 质量分数和不同重均相对分子质量的精细壳聚糖制品 ,用酸碱滴定法测定壳聚糖 -NH2 质量分数 ,用激光散射仪测定壳聚糖的重均相对分子质量 .结果 :所制得壳聚糖的 -NH2 质量分数分别为 :6 1%、74 %、82 %、86 %、99% ,对应的重均相对分子质量分别为 :8 0 4× 10 6 、7 5 8× 10 6 、8 6 0× 10 6 、5 91× 10 6 、3 2 2×10 6 .利用室温、反应时间为 7d的制备方法所得的壳聚糖 -NH2 质量分数较高且重均相对分子质量大 .结论 :反应温度为 14 0℃、反应时间为 1～ 4h可获得 -NH2 质量分数高而重均相对分子质量小的壳聚糖制品 ;反应温度为 30℃、反应时间为 7d可获得 -NH2 质量分数较高而重均相对分子质量大的壳聚糖制品 。

Aim:To prepare chitosans with different weight average molecular weights ( W) and free amino- group contents, and to develop the method for determining W of chitosans using laser light scattering technique. Methods: Under different reaction conditions of short time-high temperature and low temperature-long time to prepare chitosans with different W s and free amino-group contents, using laser scattering technique and acid-base titration to determine W s and free amino-group contents respectively. Results: Free amino-group contents of 61%,74%,82%,86%,99%, and W s of 8 04×10 6, 7 58×10 6, 8 60×10 6, 5 91×10 6, 3 22×10 6 were obtained in different conditions. Conclusion: The application of low temperature-long reaction time method is proved to be able to obtain chitosans with high free amino-group contents and W s. High temperature-short time leads to low W s and high free amino-group contents.