| Abstract: | A method consisting of cation‐selective exhaustive injection and sweeping (CSEI‐sweeping) as online preconcentration followed by a cyclodextrin modified electrokinetic chromatography (CDEKC) enantioseparation has been developed for the simultaneous determination of two brompheniramine enantiomers in rat plasma. In this method, analytes were electrokinetically injected at a voltage of 8 kV for 80 s in a fused‐silica capillary. Prior to the injection, the capillary was rinsed with 50 mM phosphate buffer of pH 3.5, followed by a plug of a higher conductivity buffer (150 mM phosphate pH 3.5, 20 psi, 6 min) and a plug of water (0.5 psi, 5 s). Separation was carried out applying –20 kV in 50 mM phosphate buffer, pH 3.5, containing 10% v/v ACN and 30 mg/mL sulfated‐β‐cyclodextrin (S‐β‐CD). Analytical signals were monitored at 210 nm. The detection sensitivity of brompheniramine enantiomers was enhanced by about 2400‐fold compared to the normal injection mode (hydrodynamic injection for 3 s at 0.5 psi, with a BGE of 50 mM phosphate buffer containing 20 mg/mL S‐β‐CD at pH 3.5), and LLOQ of two enantiomers were both 0.0100 μg/mL. In addition, this method had fairly good repeatability and showed promising capabilities in the application of stereoselective pharmacokinetic investigations for brompheniramine enantiomers in rat. |
