Effects on Enantioselectivity by the Use of Polysaccharide‐Based Columns by Multimodal Elution

Abstract

The effects in chiral recognition of polysaccharide‐based stationary phases by changing the chromatographic mode and elution conditions were investigated for a series of three congeneric chiral sulfoxides: omeprazole, lanzoprazole and pantoprazole and the hydroxyl compound metyrapol. They were chromatographically analyzed at normal, polar, organic, and reversed‐phase elution modes, under the same conditions, with columns of cellulose and amylose tris(3,5‐dimethylphenylcarbamate), amylose tris(3,5‐dimethoxy‐phenylcarbamate), and amylose tris[(S)‐1‐phenylethylcarbamate] phases. This systematic, comparative study of the four chiral phases using a single column on the three different chromatographic modes, has highlighted that changing the chromatographic mode and/or composition of the mobile phase can dramatically affect the enantioselectivity and/or enantioresolution of the polysaccharide‐based columns. These differences were due solely to mobile phase effect and not to column batch effect. The quality of the performance of the four columns was maintained during the complete study. Excellent enantioresolutions were obtained for the four chiral compounds in two out of the four chiral phases in at least two of the three chromatographic modes.

Keywords:

• Enantioseparation
• Multimodal elution
• Benzimidazoles
• Metyrapol

Acknowledgments

The authors acknowledge the financial support and grants from Fundação de Amparo a Pesquisa do Estado de São Paulo (FAPESP). A grant from Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) is also acknowledged.