Institut de Chimie Organique et Analytique (ICOA), Université d'Orléans, CNRS UMR 6005, B.P. 6759, rue de Chartres, 45067 Orléans cedex 2, France.
J Chromatogr A. 2012 Nov 30;1266:34-42. doi: 10.1016/j.chroma.2012.09.068. Epub 2012 Oct 12.
The recent introduction of new stationary phases for liquid chromatography based on superficially porous particles, called core-shell or fused-core, dramatically improved the separation performances through very high efficiency, due mainly to reduced eddy diffusion. However, few studies have evaluated the retention and selectivity of C18 phases based on such particles, despite some retention order change reported in literature between some of these phases. The carotenoid test has been developed a few years ago in the goal to compare the chromatographic properties of C18 bonded phases. Based on the analysis of carotenoid pigments by using Supercritical Fluid Chromatography (SFC), it allows, with a single analysis, to measure three main properties of reversed phase chromatography stationary phases: hydrophobicity, polar surface activity and shape selectivity. Previous studies showed the effect of the endcapping treatment, the bonding density, the pore size, and the type of bonding (monomeric vs. polymeric) on these studied properties, and described the classification map used for a direct column comparison. It was applied to ten ODS superficially porous stationary phases, showing varied chromatographic behaviors amongst these phases. As expected, due to the lower specific surface area, these superficially porous phases are less hydrophobic than the fully porous one. In regards of the polar surface activity (residual silanols) and to the shape selectivity, some of these superficially porous phases display close chromatographic properties (Poroshell 120, Halo C18, Ascentis Express, Accucore C18, Nucleoshell C18 on one side and Aeris Wide pore, Aeris peptide and Kinetex XDB on the other side), whereas others, Kinetex C18 and Halo peptide ES C18 display more specific ones. Besides, they can be compared to classical fully porous phases, in the goal to improve method transfer from fully to superficially porous particles. By the way, the paper also report the extension of the test to other ligands such as naphtyl, cholester, phenyl-hexyl, or to the new ODS bonded phases, such as charge surface hybrid phases, High Strength Silica, and Hybrid ones, and also presents results for identical brands using different particle size, such as Luna and Synergi phases. Phenyl-hexyl and napthyl ligands show rather close properties, low hydrophobicity, high polar surface activity and specific shape selectivity, whereas, at the opposite, the cholester phase display a polymeric behavior and a high hydrophobicity. Finally, additional classical (fully porous particles) C18 bonded phases are also reported to complete the data set presented in previous papers.
近年来，基于表面多孔颗粒的新型液相色谱固定相（称为核壳或融合核）的引入极大地提高了分离性能，这主要得益于涡流扩散的减少。然而，尽管文献中报道了一些这些固定相之间的保留顺序变化，但很少有研究评估基于此类颗粒的 C18 固定相的保留和选择性。
几年前开发了类胡萝卜素测试，以比较 C18 键合固定相的色谱性质。基于使用超临界流体色谱法（SFC）分析类胡萝卜素色素，它允许通过单次分析测量反相色谱固定相的三种主要性质：疏水性、极性表面活性和形状选择性。以前的研究表明端基封端处理、键合密度、孔径和键合类型（单体与聚合物）对这些研究性质的影响，并描述了用于直接柱比较的分类图。它被应用于十种 ODS 表面多孔固定相，显示出这些相之间不同的色谱行为。由于比表面积较低，这些表面多孔相的疏水性低于全多孔相。至于极性表面活性（残留硅醇）和形状选择性，一些表面多孔相显示出相近的色谱性质（Poroshell 120、Halo C18、Ascentis Express、Accucore C18、Nucleoshell C18 位于一侧，Aeris Wide pore、Aeris peptide 和 Kinetex XDB 位于另一侧），而另一些，Kinetex C18 和 Halo peptide ES C18 则显示出更特殊的性质。此外，它们可以与经典的全多孔相进行比较，以改善从全多孔颗粒到表面多孔颗粒的方法转移。顺便说一句，本文还报告了将该测试扩展到其他配体，如萘基、胆甾醇、苯基-己基，或扩展到新的 ODS 键合相，如电荷表面混合相、高强度硅胶和混合相，以及使用不同粒径的相同品牌的结果，如 Luna 和 Synergi 相。苯基-己基和萘基配体表现出相当接近的性质，疏水性低，极性表面活性高，形状选择性特异性高，而相反，胆甾醇相表现出聚合行为和高疏水性。最后，还报告了其他经典的（全多孔颗粒）C18 键合相，以补充以前文献中提出的数据组。
