Development of a modified partial filling method in capillary electrophoresis using two chiral plugs for the simultaneous enantioseparation of chiral drugs: Comparison with mixed chiral selector capillary electrophoresis

In this study, a chiral CE method was developed based on the partial filling technique with two chiral plugs for the simultaneous enantioseparation of some racemic drugs, including baclofen, carvedilol, cetirizine, chlorpheniramine, citalopram, fluoxetine, hydroxyzine, propranolol, tramadol, trihexyphenidyl. This method of capillary filling involves the application of two adjacent chiral plugs containing the same BGE, but with different chiral selectors in the plugs for the enantioseparation of a mixture of drugs which cannot be separated with single or mixed chiral selectors. By using this method, each plug can separate the enantiomers independently (same as a single chiral selector modified CE) and the possible interactions between the chiral selectors would be inhibited. The best results were obtained using a fused silica capillary (60 cm × 50 μm id (50 cm effective length)) with phosphate buffer (100 mM, pH 3.0) containing 10 mM hydroxypropyl-α/β-cyclodextrin and 10% (w/v) maltodextrin and detected by UV at 214 nm. The influence of the length and order of the chiral plugs on the enantioresolution was also studied and optimized. The proposed method was compared with a mixed chiral selector-CE system with a combination of hydroxypropyl-α-cyclodextrin/hydroxypropyl-β-cyclodextrin and maltodextrin in the BGE. According to the results, the modified partial filling method is a simple and efficient method for the simultaneous chiral separation and offers appropriate migration times and resolutions compared to the results obtained from mixed chiral selector CE.