Abstract
Chiral analysis of beta-adrenergic blockers in human plasma is an important research area due to their different pharmaceutical activities. The solid phase extraction of alprenolol, carazolol, metoprolol, oxprenolol from human plasma was achieved on C(18) cartridges using phosphate buffer (50 mM, pH 9.0) followed by elution with methanol containing 0.1% acetic acid. Chiral-HPLC was carried out on CelluCoat (250 x 4.6 mm, 5.0 mu m silica particle size) column using different combinations of n-heptane-ethanol-diethylamine at 1.0 and 2.0 mL min(-1) flow rates, respectively. The detection was achieved at 225 nm with 27 +/- A 1 A degrees C as working temperature. The chromatographic parameters, i.e., retention (k), separation (alpha) and resolution (Rs) factors ranged from 0.26 to 10.64, 1.12 to 2.10 and 1.05 to 2.26, respectively. The binding differences of enantiomeric concentrations of oxprenolol, carazolol, alprenolol, and metoprolol were 0.12, 0.08, 0.05, and 0.01, respectively. These values suggest that their activities may be in the order of oxprenolol > carazolol > alprenolol > metoprolol. The reported SPE-Chiral HPLC methods may be used to study the enantiomeric concentrations of these beta-adrenergic blockers in human and other animal plasmas for further studies.