Chiral Assay of Atenolol Present in Microdialysis and Plasma Samples of Rats Using Chiral CBH as Stationary Phase

Two different enantioselective chiral chromatographic methods were developed and validated to investigate the disposition of the β1‐receptor antagonist atenolol in blood and in brain extracellular fluid of rats (tissue dialysates). System A for the plasma samples was a one‐column chromatographic system with a Chiral CBH column with an aqueous buffer as mobile phase into which cellobiose was added for selective regulation of the retention of the internal standard, (S)‐metoprolol. The plasma samples were analysed after a simple extraction procedure. The limit of quantitation was 0.2 μg/ml for the atenolol enantiomers. The repeatability of the medium concentration quality control plasma sample (6.0 μg rac‐atenolol/ml) was 11–18% for the enantiomers. The dynamic linear range of the plasma samples was 0.5–20 μg/ml. For system B, since atenolol is an extremely hydrophilic drug, the tissue dialysate sample required a much more sensitive system as compared to the plasma samples. A coupled column system was used for peak compression of the enantiomers in the eluate after the separation on the Chiral CBH column, hence increasing the detection sensitivity. The limit of quantification was 0.045 μg/ml for the atenolol enantiomers in artificial CSF. The repeatability of the medium concentration quality control samples (0.1 and 4.0 μg rac‐atenolol/ml in artificial CSF and Hepes Ringer, respectively) was 2.8–9.3% for the two enantiomers. The dynamic linear range of the brain samples was 0.05–1.0 and 0.5–20 μg/ml in artificial CSF and Hepes Ringer, respectively. Chirality 9:329–334, 1997. © 1997 Wiley‐Liss, Inc.