Enantiomeric separation of diuretics on a novel Pirkle-type chiral stationary phase.

A newly developed Pirkle-type straight chiral stationary phase (CSP), based on the 3,5-dinitrobenzoyl derivative of 1,2 diphenylethylene-diamine and known as ULMO, has been successfully applied to the direct resolution of the enantiomers of several diuretics by liquid chromatography. In this study, the effect of changes in the mobile phase and the intrinsic stereoselective properties of this CSP towards a specific racemate are determined experimentally. A mobile phase consisting of n-hexane and 2-propanol appears most appropriate for the chiral separation of the tested diuretics on the ULMO-column.