In reversed-phase liquid chromatography, solute retention is primarily influenced by interactions between a nonpolar stationary phase and a moderately polar hydro-organic mobile phase, based on the solute lipophilicity. However, challenges regarding retention and peak tailing can arise due to ionic interactions between positively charged analytes and free silanols present on silica-based stationary phases. To address these challenges, incorporating surfactants and ionic liquids (ILs) into the mobile phase offers an effective solution. These additives synergistically enhance chromatographic performance through electrostatic and lipophilic interactions, which enable fine-tuning of selectivity and improved separation efficiency. This study explores the chromatographic behaviour of several basic compounds in aqueous mixtures containing the anionic surfactant sodium dodecyl sulphate (SDS), above its critical micellar concentration, combined with various 1-alkyl-3-methylimidazolium-based ionic liquids (ILs) featuring chloride, tetrafluoroborate, and hexafluorophosphate anions, all without the addition of organic solvents. Specifically, this research investigates the influence of different anion types within the ILs and considers the impact of the IL cations. Analysis of solute peak profiles reveals narrow and symmetrical peaks. By introducing tetrafluoroborate and hexafluorophosphate IL anions into a mobile phase that contains an anionic surfactant, the study sheds light on the interactions occurring within the chromatographic column. This enhanced understanding of the combined effects of surfactants and ILs contributes to refining chromatographic methodologies. This research highlights the importance of carefully selecting the appropriate IL when incorporating it into a micellar mobile phase alongside SDS. This combination results in practical retention times that surpass the performance achieved with either the surfactant or IL alone in the mobile phase. The study particularly emphasises the impact of the IL anion, especially in the absence of SDS and organic solvents. This unveils interactions that are otherwise obscured in micellar and hydro-organic media, providing new insights into chromatographic dynamics.

中文翻译：

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以十二烷基硫酸钠和咪唑鎓基离子液体为流动相试剂的水液色谱中阳离子和阴离子的作用


在反相液相色谱中，基于溶质的亲脂性，溶质保留主要受到非极性固定相和中等极性水有机流动相之间相互作用的影响。然而，由于带正电的分析物和二氧化硅基固定相上存在的游离硅烷醇之间的离子相互作用，可能会出现保留和峰拖尾方面的挑战。为了应对这些挑战，将表面活性剂和离子液体 (IL) 掺入流动相中提供了有效的解决方案。这些添加剂通过静电和亲脂相互作用协同增强色谱性能，从而能够微调选择性并提高分离效率。本研究探讨了几种碱性化合物在含有阴离子表面活性剂十二烷基硫酸钠 (SDS) 的水性混合物中的色谱行为（高于其临界胶束浓度），并结合各种以氯化物为特征的 1-烷基-3-甲基咪唑鎓基离子液体 (IL)，四氟硼酸根和六氟磷酸根阴离子，均无需添加有机溶剂。具体来说，本研究调查了 IL 内不同阴离子类型的影响，并考虑了 IL 阳离子的影响。溶质峰轮廓分析揭示了狭窄且对称的峰。通过将四氟硼酸盐和六氟磷酸盐 IL 阴离子引入含有阴离子表面活性剂的流动相中，该研究揭示了色谱柱内发生的相互作用。增强对表面活性剂和离子液体的综合作用的理解有助于改进色谱方法。 这项研究强调了在将 IL 与 SDS 一起加入胶束流动相时仔细选择合适的 IL 的重要性。这种组合的实际保留时间超过了流动相中单独使用表面活性剂或 IL 所达到的性能。该研究特别强调了 IL 阴离子的影响，尤其是在没有 SDS 和有机溶剂的情况下。这揭示了胶束和水有机介质中隐藏的相互作用，为色谱动力学提供了新的见解。