Stereoselective analysis of idrapril and its stereoisomers by reversed-phase high-performance liquid chromatography on a chiral-AGP column

Enantioselective liquid chromatography of C3-chiral 2,3-dihydro-1,2,5-benzothiadiazepin-4(5H)-one and thione 1,1-dioxides on polyacrylamide- and polysaccharide-based chiral stationary phases

Optically active synthetic and semisynthetic polymers were utilized as chiral stationary phases (CSPs) for the direct chromatographic enantioseparation of a series of 8-chloro-2,3-dihydro-3-methyl-1,2,5-benzothiadiazepin-4(5H)-one and thione 1,1-dioxide. Evaluation of stereochemical integrity of chiral analytes was assessed by enantioselective temperature and flow-dependent HPLC. A stopped-flow high-performance liquid chromatography (sfHPLC) procedure was developed for the determination of the rate constants and free energy barriers of enantiomerization of enantiomers of 8-chloro-2-(3-methylbut-2-enyl)-2,3-dihydro-3-methyl-1,2,5-benzothiadiazepin-4(5H)-thione 1,1-dioxide (compound 2) in the presence of Chiraspher and Chiralcel OD CSPs. In order to study the chiroptical properties of the individual enantiomers of analytes investigated, semipreparative chromatographic resolutions were performed. The assignment of the absolute configuration was empirically established by comparing the CD spectra of the separated enantiomers with those obtained from structural analogues.

Stereoselective chromatography of cardiovascular drugs: an update

This review reports the latest achievements in chromatographic enantioseparations of various classes of cardiovascular drugs and selected applications of these methods in pharmaceutical and clinical analysis. The use of these drugs as test compounds for new chiral stationary phases and different parameters of chromatographic processes is also presented.

Direct separation of captopril diastereoisomers including their rotational isomers by RP-LC using a teicoplanin column

A direct reversed-phase liquid chromatography (LC) method has been developed for the separation and analysis of captopril and its 2R,2S diastereoisomer using a teicoplanin stationary phase. The proline containing diastereoisomers, which are known to form conformers in aqueous solution, were also separated from their rotational isomers. The influence of temperature, different organic modifiers and buffer type, concentration and pH were optimised to obtain a working resolution between the two diastereoisomers and their respective rotational isomers. The diastereoisomeric purity of several commercial captopril batches was subsequently evaluated using a 0.05% triethylammonium acetate (TEAA) buffer (pH 3.8) run at 1.0 ml/min with mobile phase reservoir and column temperature controlled at 0 degrees C. Throughout the study online UV diode array and mass spectrometry detection was carried out simultaneously to confirm that peaks eluting from the teicoplanin column were in fact captopril and not its readily converted disulphide dimer. Additionally, as a result of the greater detection sensitivity of mass spectrometry, it also facilitated a more accurate optimisation study where trace amounts of the rotational isomers were found to be present in the baseline at temperatures higher than optimum.