烯烃在Ag柱上顶替置换色谱机理的研究

Studies of Displacement Mechanism of Olefines on a Silver High Performance Liquid Chromatographic (HPLC) Column

选择环己烯、苯或甲基叔丁基醚（ＭＴＢＥ）作为高效液相色谱法（ＨＰＬＣ）流动相改性剂、正己烷为流动相时，吸附在银型磺酸键合硅胶固定相上的烯烃与流动相改性剂之间存在顶替置换作用，即烯烃的容量因子ｋ＇的对数与改性剂浓度［Ｂｍ］的对数间有很好的线性关系。由关联直线的斜率ｐ可获得烯烃置换改性剂的计量关系。但在不同流动相体系下，顶替置换过程不尽相同。在流动相改性剂浓度低于一定值时，内烯烃混合物与α－烯烃混合物都能与饱和烃分离并以不同的ｋ＇流出，各自ｌｇｋ＇值与ｌｇ［Ｂｍ］值之间也有线性关系。

An HPLC system for the study of displacement mechanism is presented. In this system, silver ion was exchanged onto a cation exchanger silica column, and n-hexane containing cyclohexene, benzene or MTBE modifier was used as mobile phase. Retention times were measured for homologues of α-olefines. Linear relations were obtained between the lgk′ and logarithm of the concentration of the modifiers. Displacement mechanism is assumed in these systems. However, displacement mechanism for different. modifiers varied with their molecular structures. When cyclohexene/hexane was used as mobile phase, it was a pure displacement process. In case of benzene/hexane displacement was the main function but the size of the alkyl group in olefine affecfed the solubility of olefine molecule in benzene. In MTBE/hexane system, there are two slopes in lgk'-lg[Bm] plot for different MTBE concentration ranges. Similar displacement mechanism were also observed for both petroleum inner olefine mixture and α-olefine mixture.