Simultaneous determination of pirlindole enantiomers and dehydropirlindoleby chiral liquid chromatography

Liquid chromatography was employed for the determination of pirlindole enan tiomers and its oxidation product dehydropirlindole (DHP). The direct separ ation of pirlindole enantiomers and DHP was achieved on a cellulose tris-(3 ,5-dimethylphenylcarbamate) chiral stationary phase (Chiralcel OD-R). Aceto nitrile was used as the organic modifier and sodium perchlorate was used as an ionic additive in the mobile phase. The influence of acetonitrile and s odium perchlorate concentrations on enantioselectivity and achiral selectiv ity towards DHP was investigated in order to find suitable conditions for t he determination of low amounts of each analyte. The mobile phase selected consisted of a mixture of acetonitrile and phosphate buffer (pH 5.0) contai ning sodium perchlorate (0.05 M) (35:65, v/v) and the UV detector was set a t 220 nm, The method developed was validated and was found to be linear in the 0.1-5 mu g ml(-1) range (r(2) = 0.999 for the three compounds). Repeata bility and the intermediate precision for the three analytes at a concentra tion of 0.1 mu g ml(-1) were about 3 and 4%, respectively. This concentrati on corresponds to the quantification of 0.1% for the minor enantiomer. Actu al determinations of enantiomeric purity for single enantiomers of pirlindo le were performed. (C) 1998 Elsevier Science B.V. All rights reserved.