Chiral separation of oxprenolol by affinity electrokinetic chromatography-partial filling technique using human serum albumin as chiral selector

The intrinsic characteristics of capillary electrophoresis have made this technique a powerful tool in the chiral separation field. The present paper deals with the enantiomeric separation of oxprenolol enantiomers by affinity electrokinetic chromatography-partial filling technique using human serum albumin (HSA) as chiral selector. Several experimental conditions and variables affecting the separation such as pH, HSA concentration and plug length, background electrolyte concentration, temperature and voltage were studied. Baseline separation of oxprenolol enantiomers was obtained in less than 8 min under the following selected conditions: electrophoretic buffer composed of 50 mM Tris-(hydroximethyl)-aminomethane (Tris) at pH 8.5; 190 μM HSA solution applied at 50 mbar for 225 s as chiral selector; oxprenolol samples contained 190 μM HSA solution injected hydrodynamically at 30 mbar for 2 s and the electrophoretic runs performed at 30 °C applying 15 kV voltage. The proposed methodology was applied for the analysis of two pharmaceutical preparations. Resolution, accuracy, reproducibility, speed and cost of the proposed method make it suitable for quality control of the enantiomeric composition of oxprenolol in drugs. The results show that a different affinity between oxprenolol enantiomers and HSA exists and can contribute to the pharmacokinetic differentiation of these enantiomers.