Enantioselective analysis of atenolol in biologic fluids: comparison of liquid–liquid and solid-phase extraction methods

In this study we evaluated a liquid–liquid extraction procedure and a solid-phase extraction procedure for sample preparation for the enantioselective analysis of atenolol in plasma and urine by high-performance liquid chromatography. A Chiralcel OD-H column was used for the resolution of atenolol enantiomers with hexane–ethanol (85:15, v/v) plus 0.1% diethylamine as the mobile phase. In the liquid–liquid extraction procedure, atenolol was extracted from alkalinized body fluids with 5 ml chloroform–2-propanol (4:1, v/v). In the solid-phase extraction procedure, atenolol was isolated from plasma using a C8 column and methanol. Both extraction procedures were efficient in recovering atenolol and removing endogenous interferents. The RSDs and deviation from nominal values were lower than 10% for both within-day and between-day assays. The results show that there were no statistically significant differences in between-day variation. The t-test showed that there were no significant differences between the real concentrations and the determined concentrations. The limit of quantitation was 10 ng/ml and the linear range was 10–5000 ng/ml for both methods. These methods can be used in pharmacokinetic studies.