两性离子为流动相离子色谱法测定常见有机酸探讨

Research for detecting organic acids by ion chromatography with zwitterions

采用KOH和不同浓度的两性物质CAPS为混合流动相,在AS17阴离子交换柱上,抑制电导检测,分离草酸、苯甲酸、水杨酸、柠檬酸、邻苯二甲酸等多种常规的有机酸,以考察两性物质对各有机酸保留时间的影响。从所做实验发现低浓度的两性物质的加入可以缩短各有机酸的保留时间,但是当流动相中的两性物质浓度变大时,有机酸的保留时间反而增加。因此就两性物质对有机酸的保留影响来看,只有当两性离子在一定的浓度范围内,才能缩短保留时间,提高分离效率。

Mixture of KOH and zwitterions CAPS are used as mobile phase to separate organic acids, such as oxalic acid, benzene monocarbonic acid, salicylic acid, and citric acid.From the experiment we can see that when the concentration of CAPS is low, the retention time of five organic acid anion are shortened. With the concentration of CAPS increases , all the retention time increase at the same time. The conclusion is only when the concentration of CAPS within a appropriate range, the effect is effective in shortening the retention of organic acid anions, especially for the strong reserved anions.