Reversed-phase high-performance liquid chromatographic analysis of atenolol enantiomers in rat hepatic microsome after chiral derivatizaton with 2,3,4,6,-tetra-O-acetyl-beta-D-glycopyranosyl isothiocyanate.

A reversed-phase high-performance liquid chromatographic method for the determination of the enantiomers of atenolol in rat hepatic microsome has been developed. Racemic atenolol was extracted from alkalinized rat hepatic microsome by ethyl acetate. The organic layer was dried with anhydrous sodium sulfate and evaporated using a gentle stream of air. Atenolol racemic compound was derivatized with 2,3,4,6-tetra-O-acetyl-beta-D-glycopyranosyl isothiocyanate at 35 degrees C for 30 min to form diastereomers. After removal of excess solvent, the diastereomers were dissolved in phosphate buffer (pH 4.6)-acetonitrile (50:30). The diastereomers were separated on a Shimadzu CLC-C18 column (10 microm particle size, 10 cm x 0.46 cm I.D.) with a mobile phase of phosphate buffer-methanol-acetonitrile (50:20:30, v/v) at a flow-rate of 0.5 ml/min. A UV-VIS detector was operated at 254 nm. For each enantiomer, the limit of detection was 0.055 microg/ml (signal-to-noise ratio 3) and the limit of quantification (signal-to-noise ratio 10) was 0.145 microg/ml (RSD <10%). In the range 0.145-20 microg/ml, intra-day coefficients of variation were 1.0-7.0% and inter-day coefficients of variation were 0.4-16.5% for each enantiomer. The assay was applied to determine the concentrations of atenolol enantiomers in rat hepatic microsome as a function of time after incubation of racemic atenolol.