Enantioseparation and Quantitative Analysis of Citalopram by Capillary Electrophoresis with Maltose as the Chiral Selector and Its Separation Mechanism

Chiral separation of citalopram(CIT) was performed by capillary zone electrophoresis (CZE) using maltose as the chiral additive. The effect of the concentration of electrophoretic running buffer, its pH, concentration of maltose, and the applied running voltage were investigated. The optimized conditions were obtained with 20 kV as the running voltage, and a running buffer of 40 % (w/w) maltose in 8.0 × 10−2 M phosphate (pH 5.0). Good resolution of citalopram enantiomers was achieved and the Rs were 2.3 under optimal conditions. The quantitative analysis of citalopram was performed. The linear range of concentration of R-(–)-CIT to their peak areas was 0.05–4.00 mg ml−1. The LOD of the two enantiomers were 4.53 × 10−2 mg/ml and 4.73 × 10−2 mg ml−1, respectively. The regression coefficient was more than 0.9978. The interaction between CIT and maltose was studied by fluorescence spectra method and the mechanism of the enantioseparation was also researched. It was proved that the chiral recognition ability of maltose is related to the concentration of maltose. Maltose molecules begin to aggregate to form hydrophobic cavities, when the concentration of maltose exceeds a critical concentration. The enantioselectivity is attributed to the stereo recognition of the cavities formed by aggregating maltose molecules.