Meng Haoxiang, Ding Sihui, Xue Song, Liu Siyao, Wu Qing, Zhang Qi
School of Pharmacy, Jiangsu University, Zhenjiang, 212013, PR China.
Affiliated Hospital of Jiangsu University, Zhenjiang, 212001, PR China.
Anal Chim Acta. 2025 Jan 22;1336:343467. doi: 10.1016/j.aca.2024.343467. Epub 2024 Nov 22.
Capillary electrophoresis (CE) is a highly versatile separation technique widely used in analytical chemistry. Traditionally, CE can be categorized as either aqueous or non-aqueous systems based on the buffer solvents employed. For decades, non-aqueous CE has been predominantly associated with the use of organic solvents, a perception deeply ingrained in the scientific community. However, growing concerns about the health and environmental impacts of these solvents, driven by the principles of green chemistry, have prompted a reevaluation of their use. In response to these concerns, our group recently introduced a deep eutectic solvent (DES), specifically Proline:Urea, as an innovative and eco-friendly separation medium for CE. This approach not only enhances the sustainability of CE separations but also offers a new perspective for the development of innovative CE separation media.
Building on our previous work, here we report the use of the second DES, Betaine:Urea (BU), as a new separation medium that offers further improved performance for CE applications. The DES was systematically characterized, with key physical properties relevant to CE separations, such as thermal properties, viscosity, dielectric constant, Joule heating effect, and UV transmittance, being thoroughly examined. Using a complex sample of 10 structurally similar naphthalene derivatives, we demonstrated the efficiency of BU in capillary zone electrophoresis (CZE) for separating analytes with varying charges (including cations, neutrals, and anions) and sizes. Additionally, we established the first micellar electrokinetic chromatography (MEKC) system in this DES using sodium dodecyl sulfate (SDS) as the surfactant. This system successfully resolved 6 structurally similar neutrals that could not be separated by conventional aqueous SDS-MEKC, highlighting the versatility of this DES-type separation medium. Furthermore, BU showed several advantages over the previously reported DES, Proline:Urea, particularly in terms of stability, viscosity, and Joule heating effects.
This study holds the potential to challenge the traditional notion that "CE separation media are merely categorized into aqueous and organic solvents". Given that DESs are "designer" solvents with highly tunable properties and environmentally friendly characteristics, the introduction of BU as a viable alternative to traditional solvents not only expands the media available for CE separations, but also offers a more efficient and potentially more sustainable option for specific analyses.
毛细管电泳（CE）是一种在分析化学中广泛应用的高度通用的分离技术。传统上，根据所使用的缓冲溶剂，CE可分为水性或非水性系统。几十年来，非水性CE主要与有机溶剂的使用相关联，这种观念在科学界根深蒂固。然而，出于绿色化学原则，对这些溶剂对健康和环境影响的日益关注促使人们重新评估其使用。为回应这些担忧，我们团队最近引入了一种深共熔溶剂（DES），即脯氨酸：尿素，作为一种用于CE的创新且环保的分离介质。这种方法不仅提高了CE分离的可持续性，还为创新型CE分离介质的开发提供了新视角。
基于我们之前的工作，在此我们报告使用第二种DES，即甜菜碱：尿素（BU），作为一种新的分离介质，它为CE应用提供了进一步提升的性能。对该DES进行了系统表征，全面考察了与CE分离相关的关键物理性质，如热性质、粘度、介电常数、焦耳热效应和紫外透过率。使用包含10种结构相似的萘衍生物的复杂样品，我们证明了BU在毛细管区带电泳（CZE）中分离具有不同电荷（包括阳离子、中性分子和阴离子）及尺寸的分析物的效率。此外，我们在这种DES中使用十二烷基硫酸钠（SDS）作为表面活性剂建立了首个胶束电动色谱（MEKC）系统。该系统成功分离了6种传统水性SDS - MEKC无法分离的结构相似的中性分子，突出了这种DES型分离介质的多功能性。此外，与先前报道的DES脯氨酸：尿素相比，BU显示出几个优点，特别是在稳定性、粘度和焦耳热效应方面。
本研究有可能挑战“CE分离介质仅分为水性和有机溶剂”这一传统观念。鉴于DES是具有高度可调性质和环境友好特性的“设计型”溶剂，将BU作为传统溶剂的可行替代品引入，不仅扩展了可用于CE分离的介质，还为特定分析提供了更高效且可能更具可持续性的选择。
