Separation and quantitation of oxprenolol in urine and pharmaceutical formulations by HPLC using a Chiralpak IC and UV detection

Abstract

A stereoselective HPLC method has been developed for the simultaneous determination of oxprenolol enantiomers in urine and pharmaceutical products. Enantiomeric resolution of oxprenolol was achieved on cellulose tris(3,5-dichlorophenylcarbamate) immobilized onto a 5 μm spherical porous silica chiral stationary phase (CSP) known as Chiralpak IC with UV detection at 273 nm. The mobile phase consisted of n-hexane:isopropanol:triethylamine 70:30:0.1 (v/v/v) at a flow rate of 1.0 cm3/min. The method was validated for its linearity, accuracy, precision, and robustness. The calibration curves were linear over the range of 0.5–75 μg/cm3, with a detection limit of 0.1 μg/cm3 for each enantiomer. An average recovery of 99.0% and a mean relative standard deviation of 2.6% at 40.0 μg/cm3 for S-(−)- and R-(+)-enantiomers were obtained. The overall recoveries of oxprenolol enantiomers from pharmaceutical formulations were in the range 97.5–99.0%, with RSDs ranging from 0.6 to 0.8%. The mean extraction efficiency of oxprenolol from urine was in the range of 86.0–93.0% at 0.5–5 μg/cm3 for each enantiomer. The assay method proved to be suitable as a chiral quality control for oxprenolol formulations using HPLC and for therapeutic drug monitoring.