HPLC separation of dihydropyridine derivatives enantiomers with emphasis on elution order using polysaccharide‐based chiral columns

Abstract

The separation of enantiomers of five chiral dihydropyridine derivatives was studied on five different polysaccharide-based chiral HPLC columns with various normal-phase (NP), polar organic, and reversed-phase eluents. Along with the successful separation of analyte enantiomers, the emphasis of this study was on enantiomer elution order (EEO) with various columns and mobile phase composition. The interesting phenomenon of reversal of EEO, recently reported in the case of amlodipine (AML) depending on the concentration of formic acid in acetonitrile, was also confirmed with NP eluents. Under RP conditions at relatively low water content, the EEO of AML could also be reverted by varying the concentration of formic acid in the mobile phase. However, at higher water content the same parameter did not affect the EEO, but only induced gradual decrease in resolution up to complete co-elution of enantiomers. Additionally, in organic-aqueous mobile phases retention factors decreased with increasing water content but only up to 20% (v/v), while above this concentration the expected typical RP behavior was observed. The presence of the commonly used additive diethylamine in the mobile phase seems important for observing a reversal in EEO with increasing concentration of formic acid. The reversal of the EEO was characteristic of AML only and was not observed for any of other dihydropyridines included in this study.

High‐performance liquid chromatography enantioseparation of polyhalogenated 4,4′‐bipyridines on polysaccharide‐based chiral stationary phases under multimodal elution

“…Obviously, on CSPs 2 and 3 , the retention mechanism of 7 and 12 changed depending on the amount of H 2 O. Indeed, as previously observed by other authors , a competition between water and analyte can occur as both interact with the binding sites of the polysaccharide selector. Thus, two types of mechanisms can be involved: (i) at lower concentrations (10%), water behaves as the strongest solvent as it occurs under HILIC conditions (Fig.…”

HPLC separation of enantiomers of chiral arylpropionic acid derivatives using polysaccharide‐based chiral columns and normal‐phase eluents with emphasis on elution order

“…; Supporting Information Table S1). Several examples of opposite elution order of analytes on cellulose‐ and amylose‐based columns have been described previously .…”

Liquid Chromatography Enantioseparations of Halogenated Compounds on Polysaccharide‐Based Chiral Stationary Phases: Role of Halogen Substituents in Molecular Recognition

“…6) was performed by Cannazza et al on Chiralcel OD-RH (150 × 4.6 mm, 5 μm) by using water/ACN 60:40 as mobile phase. 43 In this study, the retention of amlodipine was significantly long in the n-hexane/IPA-based eluents. These compounds are effective aldose reductase inhibitors and potential drugs for various diabetic complications.…”