Assessment of chiral stationary phases for suitability for combined enantiomeric impurity/related substances assays

Resolution, determination of enantiomeric purity and chiral recognition mechanism of new xanthone derivatives on (S,S)-whelk-O1 stationary phase

The enantioresolution and determination of the enantiomeric purity of 32 new xanthone derivatives, synthesized in enantiomerically pure form, were investigated on (S,S)-Whelk-O1 chiral stationary phase (CSP). Enantioselectivity and resolution (α and R_S ) with values ranging from 1.41-6.25 and from 1.29-17.20, respectively, were achieved. The elution was in polar organic mode with acetonitrile/methanol (50:50 v/v) as mobile phase and, generally, the (R)-enantiomer was the first to elute. The enantiomeric excess (ee) for all synthesized xanthone derivatives was higher than 99%. All the enantiomeric pairs were enantioseparated, even those without an aromatic moiety linked to the stereogenic center. Computational studies for molecular docking were carried out to perform a qualitative analysis of the enantioresolution and to explore the chiral recognition mechanisms. The in silico results were consistent with the chromatographic parameters and elution orders. The interactions between the CSP and the xanthone derivatives involved in the chromatographic enantioseparation were elucidated.

New validated HPLC methodology for the determination of (-)-trans-paroxetine and its enantiomer in pharmaceutical formulations with use of ovomucoid chiral stationary phase

A new chromatographic method for the enantioseparation and the determination of (−)-trans-paroxetine and (+)-trans-paroxetine has been developed with the aid of amylose ovomucoid-based chiral stationary phase. The method is faster and five times more sensitive than procedures recommended previously: limit of detection and limit of quantification are 5 and 16 ng/mL, respectively [modified (Ferretti et al. in J Chromatogr B 710:157–164, 1998): 20 and 60 ng/mL]. It was carefully validated and applied for the determination of (−)-trans-paroxetine and (+)-trans-paroxetine in Parogen (Mc Dermott Laboratories Ltd.) and Xetanor (Actavis) coated tablets.

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Enantioresolution of chiral derivatives of xanthones on (S,S)-Whelk-O1 and L-phenylglycine stationary phases and chiral recognition mechanism by docking approach for (S,S)-Whelk-O1

The resolution of seven enantiomeric pairs of chiral derivatives of xanthones (CDXs) on (S,S)-Whelk-O1 and L-phenylglycine chiral stationary phases (CSPs) was systematically investigated using multimodal elution conditions (normal-phase, polar-organic, and reversed-phase). The (S,S)-Whelk-O1 CSP, under polar-organic conditions, demonstrated a very good power of resolution for the CDXs possessing an aromatic moiety linked to the stereogenic center with separation factor and resolution factor ranging from 1.91 to 7.55 and from 6.71 to 24.16, respectively. The chiral recognition mechanisms were also investigated for (S,S)-Whelk-O1 CSP by molecular docking technique. Data regarding the CSP-CDX molecular conformations and interactions were retrieved. These results were in accordance with the experimental chromatographic parameters regarding enantioselectivity and enantiomer elution order. The results of the present study fulfilled the initial objectives of enantioselective studies of CDXs and elucidation of intermolecular CSP-CDX interactions.