Direct injection analysis of atenolol enantiomers in plasma using an achiral/chiral coupled column HPLC system

A novel HPLC system was developed with an achiral/chiral coupled column for the direct injection analysis of atenolol (AT) enantiomers in plasma. The system consists of a size-exclusion column, an ODS silica column and a newly developed beta-cyclodextrin perphenylcarbamate(ph-beta-CD)-bonded silica column connected in a series via two switching valves. The neat plasma sample was directly injected onto the size-exclusion column, and the deproteinized fraction of AT enantiomers was concentrated on the ODS silica column. The enantiomers were then transferred and separated mutually on the ph-beta-CD silica column. The calibration line for each of the AT enantiomers was linear in the range of plasma concentration of 10-200 ng/ml (r > 0.9997) with good reproducibility (CV < 9.7%, n = 20). The recoveries from plasma were almost complete (> 97.4%) for both enantiomers. One analysis finished within 30 min. The developed system was applied to the enantioselective determination of plasma concentration-time curve of AT after the oral administration of racemic AT to a healthy volunteer.