Yang S, Bumgarner J G, Khaledi M G
Department of Chemistry, North Carolina State University, Raleigh 27695-8204, USA.
J Chromatogr A. 1996 Jul 12;738(2):265-74. doi: 10.1016/0021-9673(96)00080-5.
Retention behavior in micellar electrokinetic chromatography (MEKC) is investigated using linear solvation energy relationships (LSERs) for two pseudo-stationary phases, one consisting of cationic micelles of tetradecyltrimethylammonium bromide (C14TAB) and the other of an anionic triblock copolymer, poly(methyl methacrylate-ethyl acrylate-methacrylic acid) (Elvacite 2669). It was found that solutes' migration behaviors in these two MEKC systems are mainly influenced by their size (V/100) and hydrogen bonding acceptor (HBA) strength (beta). However, solutes' hydrogen bonding donor (HBD) strength (alpha) has minor effects on their migration in MEKC. The characteristics of these two systems were compared to three other previously reported anionic micellar systems of sodium dodecyl sulfate (SDS) (anionic hydrocarbon), sodium cholate (SC) (anionic bile salt) and lithium perfluorooctane sulfonate (LiPFOS) (anionic fluorocarbon). It was concluded that hydrogen bonding interactions play a major role in providing different chemical selectivity among these five MEKC systems. Both C14TAB micelles and the ionic polymer of Elvacite 2669 provide hydrogen bonding acceptor (HBA) sites for solutes, which is similar to SC micelles. In fact, C14TAB is the strongest HBA, while Elvacite 2669 has HBA strength similar to that of SC micelles. On the other hand, the fluorocarbon micelles of LiPFOS are the strongest hydrogen bond donor (HBD) micelles, followed by the weak HBD SDS micelles. In general, cavity formation has little or no effect on chemical selectivity among hydrocarbon surfactant MEKC systems (i.e., SDS, SC and C14TAB). Information obtained from the LSER analysis is used to rationalize the elution patterns in MEKC with different types of pseudo-stationary phases.
采用线性溶剂化能关系（LSERs）研究了两种假固定相在胶束电动色谱（MEKC）中的保留行为，一种假固定相由十四烷基三甲基溴化铵（C14TAB）的阳离子胶束组成，另一种由阴离子三嵌段共聚物聚（甲基丙烯酸甲酯-丙烯酸乙酯-甲基丙烯酸）（Elvacite 2669）组成。研究发现，溶质在这两种MEKC体系中的迁移行为主要受其大小（V/100）和氢键受体（HBA）强度（β）的影响。然而，溶质的氢键供体（HBD）强度（α）对其在MEKC中的迁移影响较小。将这两种体系的特征与其他三种先前报道的阴离子胶束体系进行了比较，即十二烷基硫酸钠（SDS）（阴离子烃）、胆酸钠（SC）（阴离子胆汁盐）和全氟辛烷磺酸锂（LiPFOS）（阴离子碳氟化合物）。研究得出结论，氢键相互作用在这五种MEKC体系中提供不同的化学选择性方面起主要作用。C14TAB胶束和Elvacite 2669离子聚合物都为溶质提供氢键受体（HBA）位点，这与SC胶束类似。事实上，C14TAB是最强的HBA，而Elvacite 2669的HBA强度与SC胶束相似。另一方面，LiPFOS的碳氟化合物胶束是最强的氢键供体（HBD）胶束，其次是弱HBD的SDS胶束。一般来说，空穴形成对烃类表面活性剂MEKC体系（即SDS、SC和C14TAB）之间的化学选择性影响很小或没有影响。从LSER分析中获得的信息用于合理解释不同类型假固定相在MEKC中的洗脱模式。
