Enantioseparation of drugs by means of continuous bed monolithic columns in nano-LC

A chiral continuous bed was realized by a simple one-step synthesis and used to perform enantioseparations of drugs in nano-liquid chromatography (nano-LC). The capillary format of columns of this miniaturized technique allows to easily prepare in situ the chromatographic media. The continuous bed (also called monolithic) column was synthesized employing water-soluble comonomers and hydroxypropyl-? -cyclodextrin (HP-?-CD) was selected as chiral selector. In order to make possible the one-step synthesis, HP-?-CD was previously activated as the allyl derivative. Several polymeric mixtures were studied to increase the enantiorecognition capability of the column. Analyses were carried out employing aqueous mobile phases, and the effect of organic modifiers and pH on enantiomeric resolution were studied. Among tested compounds, nomifensine and naproxen were baseline resolved, using a mobile phase containing respectively 20/80 methanol/water and 20/80 acetonitrile/water, both buffered with 0.1% triethylamine-acetate. A partial resolution was achieved also for praziquantel, metomidate and 5-methyl-5-phenyl-hydantoin.