Separation of propranolol enantiomers using chiral HPLC

Abstract

Enantiomers of pharmaceuticals may exhibit different effects because the organism serves as a chiral selector. Enantiomers can now be identified and separated using analytical techniques such as gas chromatography and high-performance liquid chromatography. The nonselective b-adrenergic blocker propranolol is used as a racemate in therapy, but only the S(-) isomer has been shown to be active. The aim of this study was to determine the mobile phase composition that would achieve optimal retention and satisfactory resolution between enantiomers and to confirm the order of elution of the enantiomers. The enantioseparation was tested in the n-heptane/ethanol/ammonia, n-heptane/ethanol/diethylamine, n-heptane/isopropanol/ ammonia and n-heptane/isopropanol/diethylamine systems. Optimal separation of enantiomers (t1=4,708; t2=5.264; Rs=1.75) was achieved with the mobile phase n-heptane/ethanol/diethylamine 80/20/0.1. The elution order was based on the retention time of the pure S(-)isomer. It was confirmed that the R(+) isomer shows higher retention.