Carboxymethylated maltodextrin as a chiral selector for the separation of some basic drug enantiomers using capillary...

In this work, carboxymethylated maltodextrin (Cm-MD) was successfully synthesized as an efficient anionic chiral selector and applied for the enantiomer separation of some basic drugs including tramadol, venlafaxine, verapamil, hydroxyzine, citalopram, fluoxetine, and amlodipine by capillary electrophoresis (CE). The synthesized chiral selector was characterized by the nuclear magnetic resonance and Fourier transform infrared spectrophotometry. Under the optimized Cm-MD modified CE conditions (background electrolyte: phosphate buffer (pH 5.0, 50 mM) containing 5% (w/v) Cm-MD; applied voltage: 20 kV; and capillary column temperature: 25 °C), successful enantiomer separation of all studied chiral drugs were observed. By comparison of Cm-MD and MD for enantiomer separation of the model drugs, it was revealed that Cm-MD exhibits a higher resolution in comparison to the MD modified CE. This enhanced resolution could be attributed to the electrostatic interactions between the cationic drugs and anionic Cm-MD and opposite direction mobility of the host-guest complex relative to the chiral analyte. The optimized Cm-MD modified CE method was successfully used for the assay of the enantiomers of citalopram and venlafaxine in commercial tablets. The proposed method showed the linear range of 5.0-150.0 mg/L and 10.0-150.0 mg/L for both enantiomers of citalopram and venlafaxine, respectively. The limits of quantification were 5.0 and 10.0 mg/L for the enantiomers of citalopram and venlafaxine, respectively. The limit of detection for all enantiomers was found to be < 3.0 mg/L. Intra- and inter-day RSDs (n = 4) were less than 9.7%. The relative errors were less than 9.4% for all enantiomers. The obtained results in this research show that Cm-MD as a new, efficient and inexpensive chiral selector can be used for enantiomer separation of basic drugs using the CE technique.