Preparation and Application of a New Ion-Pairing Chiral Stationary Phase for the Liquid Chromatographic Resolution of N-(3,5-Dinitrobenzoyl)-α-amino Acids

Abstract

A liquid chromatographic chiral stationary phase (CSP) was prepared starting from (1S, 2S)-1,2-diaminocyclohexane. The CSP containing two simple functional groups, such as a primary amino group and an ureide tethering linkage on a cyclohexane ring, was quite successful with the use of 60% 2-propanol in hexane containing 0.5% acetic acid as a mobile phase for the resolution of various N-(3,5-dinitrobenzoyl)-α-amino acids, the separation (α) and the resolution factors (R S ) being in the range of 1.12–1.23 and 1.33–2.99, respectively. In contrast, N-(3,5-dinitrobenzoyl)-α-amino acid ethyl esters and N-(3,5-dinitrobenzoyl)-α-amino acid amides were not resolved at all, or resolved very poorly on the CSP. From these results, it was concluded that the ionic or ion-paring interaction between the CSP and analytes plays a very important role for the chiral recognition. The chromatographic behaviors for the resolution of N-(3,5-dinitrobenzoyl)-α-amino acids on the CSP were found to be controlled with the variation of the type and the content of alcohol and/or acid in hexane.