Abstract

Polysaccharide-based chiral stationary phases account for a majority of chiral HPLC separations. Their behavior in normal-phase and reversed-phase modes of separation has been studied extensively. However, much less is known about their behavior in polar-organic mode. In the course of our studies on preparative separation of various cyclic imides, lactams, and acetamides on Chiralcel OD, Chiralcel OJ, Chiralpak AD, and Chiralpak AS stationary phases we sought to determine the void volumes of these columns using commonly used markers, LiNO₃, thiourea, and acetone. We were surprised to notice extensive column- and solvent-dependent deviations from ideal (unretained and unexcluded) behavior. These deviations likely result from multiple types of noncovalent interactions possible for these chiral stationary phases. Therefore, great care should be taken when choosing void volume markers for such separations. Our results indicate that with acetonitrile as a mobile phase, acetone is a suitable void volume marker for all four of the abovementioned stationary phases.

摘要

基于多糖的手性固定相占手性 HPLC 分离的大部分。它们在正相和反相分离模式下的行为已被广泛研究。然而，人们对它们在极性有机模式下的行为知之甚少。在我们研究各种环状酰亚胺、内酰胺和乙酰胺在 Chiralcel OD、Chiralcel OJ、Chiralpak AD 和 Chiralpak AS 固定相上的制备分离过程中，我们试图使用常用标记 LiNO _{3确定这些色谱柱的空隙体积}、硫脲和丙酮。我们惊讶地注意到与理想（未保留和未排除）行为的大量色谱柱和溶剂相关偏差。这些偏差可能是由于这些手性固定相可能存在多种类型的非共价相互作用。因此，在为此类分离选择空隙体积标记时应格外小心。我们的结果表明，以乙腈为流动相，丙酮是上述所有四种固定相的合适空隙体积标记物。