Institute of Physical and Analytical Chemistry, School of Exact and Natural Sciences, Tbilisi State University, Chavchavadze Ave 3, 0179 Tbilisi, Georgia.
MTA-PTE Molecular Interactions in Separation Science Research Group, Ifjúság útja 6, H-7624 Pécs, Hungary.
J Chromatogr A. 2020 Aug 2;1624:461218. doi: 10.1016/j.chroma.2020.461218. Epub 2020 May 23.
In this study, amylose- and cellulose-phenylcarbamate-based chiral columns with different chiral-selector (CS) chemistries were compared to each other for the separation of enantiomers of basic chiral analytes in acetonitrile and aqueous-acetonitrile mobile phases in HPLC. For two chemistries the amylose-based columns with coated and immobilized CSs were also compared. The comparison of CSs containing only electron-donating or electron-withdrawing substituents with those containing both electron-donating and electron-withdrawing substituents showed opposite results for the studied set of chiral analytes in the case of amylose and cellulose derivatives. Along with the chemistry of CS the focus was on the behavior of polysaccharide phenylcarbamates in acetonitrile versus aqueous acetonitrile as eluents. In agreement with earlier results, it was found that in contrast to the commonly accepted view, polysaccharide phenylcarbamates do not behave as typical reversed-phase materials for basic analytes either. In the range of water content in the mobile phase of up to 20-30% v/v the behavior of these CSs is similar to hydrophilic interaction liquid chromatography (HILIC)-type adsorbents. This means that with increasing water content in the mobile phase up to 20-30% v/v, the retention of analytes mostly decreases. The important finding of this study is that the separation efficiency improves for most analytes when switching from pure acetonitrile to aqueous acetonitrile. Therefore, in spite of reduced retention, the separation of enantiomers improves and thus, the HILIC-range of mobile phase composition, offering shorter analysis time and better peak resolution, is advantageous over pure polar-organic solvent mode. Interesting examples of enantiomer elution order (EEO) reversal were observed for some analytes based on the content of water in the mobile phase on Lux Cellulose-1 and Lux Amylose-2 columns.
在这项研究中，比较了基于直链淀粉和纤维素的苯甲酰基手性柱，这些柱具有不同的手性选择剂（CS）化学性质，用于在 HPLC 中以乙腈和水-乙腈流动相分离碱性手性分析物的对映异构体。对于两种化学性质，还比较了带有涂覆和固定 CS 的基于直链淀粉和纤维素的柱。对于研究的一组手性分析物，仅含有供电子或吸电子取代基的 CS 与同时含有供电子和吸电子取代基的 CS 相比，对于直链淀粉和纤维素衍生物，结果相反。除了 CS 的化学性质外，重点还放在多糖苯甲酰基在乙腈和水-乙腈作为洗脱剂中的行为上。与早期的结果一致，结果发现，与普遍接受的观点相反，多糖苯甲酰基对于碱性分析物也不作为典型的反相材料。在流动相中水含量的范围内，高达 20-30%v/v，这些 CS 的行为类似于亲水相互作用液相色谱（HILIC）型吸附剂。这意味着，随着流动相中水含量增加到 20-30%v/v，分析物的保留大多降低。这项研究的重要发现是，对于大多数分析物，当从纯乙腈切换到水-乙腈时，分离效率提高。因此，尽管保留时间缩短，但对映异构体的分离得到改善，因此，HILIC 范围的流动相组成，提供较短的分析时间和更好的峰分辨率，比纯极性有机溶剂模式更有利。基于 Lux Cellulose-1 和 Lux Amylose-2 柱在流动相中的水含量，观察到一些分析物的对映体洗脱顺序（EEO）反转的有趣例子。
