Liquid Chromatographic Enantiomeric Separation of Chiral Aliphatic Amines Using 2-Hydroxynaphthaldehyde as a Derivatizing Agent on Polysaccharide-Derived Chiral Stationary Phases

Abstract

A new liquid chromatographic enantiomer separation of chiral amines as 2-hydroxynaphthaldimine derivatives on several coated and immobilized chiral stationary phases (CSPs) derived from polysaccharides is described. 2-Hydroxynaphthaldehyde was introduced as a derivatizing agent for the enantiomeric separation of chiral aliphatic amines under the normal phase conditions, and was found to both enhance detection sensitivity and provide suitable interaction sites for enantiodiscrimination. Cellulose-derived CSPs, in general, exhibited better enantiomeric separation than amylose-derived CSPs. Amongst the examined six covalently bonded and four coated-type CSPs, covalently bonded Chiralpak IC, which contains a cellulose-based chiral selector, showed the best enantioseparation. The method was applied to the determination of the enantiomeric purity of commercially available (R)- and (S)-leucinol. The enantiomeric impurities of the investigated analytes procured from two suppliers were found to be 0.06–1.20%. The developed analytical method was also validated in accordance with ICH guidelines and proved to be enantioselective, sensitive and effective for the enantiomeric separation of chiral aliphatic amines as 2-hydroxynaphthaldimine derivatives under ultraviolet detection.