优化毛细管电泳法测定山药淀粉中直链/支链淀粉

Optimization of Capillary Electrophoresis for the Determination of Amylose/Amylopectin Content in Chinese Yam Starch

以市售新鲜怀山药为原料通过石灰水浸泡法制备山药粉,并通过正丁醇反复结晶法分离纯化直链淀粉与支链淀粉。利用碘做显色剂,使用毛细管电泳法测定山药淀粉中直链淀粉与支链淀粉的含量以及比率,本文分别对柠檬酸-磷酸盐缓冲液以及醋酸-醋酸盐缓冲液等不同缓冲液作为流动相进行了对比,实验发现醋酸-醋酸盐缓冲液对于分离测定直链淀粉与支链淀粉的效果较好。随后分析了不同p H条件下的醋酸-醋酸盐缓冲液进行的分离效果进行了比较,并测定其迁移率,当p H 4.8时分离效果最佳且其迁移率达到15.4。利用最佳条件使用纯的马铃薯直链淀粉与支链淀粉标准品,得出支链淀粉的保留时间约为1.8 min,而直链淀粉的保留时间约为2.9 min,对怀山药淀粉进行分析,从而得出怀山药中直链淀粉含量为19.49%。利用重复性试验以及回收率试验该方法的准确性与精确度能达到很好的效果。

Chinese yam powder was prepared by limewater immersion with fresh, commercially available Dioscorea opposita as the raw material; amylose and amylopectin were separated and purified by repeated recrystallizations using n-butanol. Using iodine ions as chromogenic agents, capillary electrophoresis was used to determine the content and ratio of amylose and amylopectin in Chinese yam starch. In this study, the use of different buffers, such as citrate-phosphate and acetate acid-acetate, was compared. The acetate acid-acetate buffer was found to be superior in the separation of amylose and amylopectin. Subsequently, the separation effects of acetate acid-acetate buffer under different pH values were compared and the electrophoretic mobilities were measured. When the pH was 4.8, the best separation effect was obtained, with an electrophoretic mobility of 15.4. Under the optimized conditions, the retention time of amylopectin and amylose was 1.8 min and 2.9 rain, respectively, with pure potato amylose and amylopectin as the standards. Dioscorea opposita starch was analyzed, and the amylose content was found to be 19.49%. Repeatability and recovery experiments confirmed the suitable accuracy and precision of this method.