Study of enantioseparation of β-blockers using amylose tris(3-chloro-5-methylphenylcarbamate) as chiral stationary phase under polar-organic, reversed-phase and hydrophilic interaction liquid chromatography conditions

Abstract

In this study, we describe the experimental variables influencing enantioseparation of twelve β-blockers when analyzed under polar-organic, reversed-phase and hydrophilic interaction liquid chromatography conditions on a column with immobilized amylose tris(3-chloro-5-methylphenylcarbamate) as chiral stationary phase. Regarding polar-organic mode, two component mobile phases consisting of methanol, ethanol or acetonitrile with the addition of basic additives such as diethylamine, triethylamine, mono-ethanolamine, ethylendiamine or trifluoroacetic acid/diethylamine mixture were evaluated. Studies of retention at different temperatures were also performed. In reversed-phase mode, mixtures consisting of methanol or acetonitrile with either aqueous boric acid-borate buffer or sodium hydrogen carbonate-carbonate buffer solutions were compared aiming to study the influence of organic modifier as well as buffer type and pH on resolution. In addition, a systematic evaluation of the retention factors of β-blockers enantiomers in hydro-organic eluents containing acetonitrile in presence of diethylamine as additive was carried out by increasing progressively the water content, in order to check for retention dependencies indicative of the interplay of both hydrophilic interaction liquid chromatography and reversed-phase modes.