Determination of enantiomers of active ingredient in pharmaceutical forms by HPLC

A validated HPLC-UV method was developed for the determination of R(-),S(+)-atenolol and R(-),S(+)-propranolol in pharmaceutical formulation. The proposed method requires no elaborate sample preparation and found to be selective, linear and repeatable within the established ranges. Atenolol and propranolol isomers were separated using a Chirex(S)_ICA/(R)_NEA (00G_3022 _E0, 250_4.6 mm) with a mobile phase of % 60 hexan, % 35 dicloromethan, %5 methanol (20:1 trifluoroacetic acid) at a flow rate of 2 ml min-1 and mobile phase of % 55 hexan, % 40 dicloromethan, %5 ethanol % 0.25 trifluoroacetic acid at a flow rate of 2ml min-1, respectively. The calibration curves of both the R(-) - atenolol and S(+) - atenolol were linear over the concentration range of 50-150 µg ml-1. The calibration curves of both the R(-)-propranolol and S(+)-propranolol were linear over the concentration range of 5-100 µg ml-1. The detection limits of R(-) and S(+)-atenolol were found to be as 12.3 µg ml-1 and 9.86 µg ml-1, respectively. The detection limits of R(-) and S(+)-propranolol were found to be as 0.61 µg ml-1 and 0.89 µg ml-1, respectively. Retention times of R(-)-propranolol and S(+)-propranolol is 12.4 min and 14.3 min, respectively. Retention times of R(-)-atenolol and S(+)-atenolol 29.4 min and 33.2 min, respectively. Detection was performed by measurement of UV absorbance at 254 nm for propranolol and 280 nm for atenolol. Timolol was used as the internal standard throughout the experimental work. The proposed method was applied to the determination of enantiomers in pharmaceutical formulation and no interference of any excipients matrices was found.Keywords: Propranolol, Atenolol, HPLC, Enantiomer separation