Phosphated maltodextrin as an anionic chiral selector for capillary electrophoresis: Application to the enantiomeric...

Chiral separation is critical in pharmaceutical analysis, as enantiomers often exhibit distinct pharmacological activities, metabolic behaviors, and toxicity profiles. Cyclodextrins have been widely employed in capillary electrophoresis (CE) owing to their well-defined cavities and strong inclusion capabilities that facilitate effective chiral recognition. However, their relatively high cost, moderate aqueous solubility, and limited compatibility with certain analytes remain important drawbacks. In contrast, maltodextrins are inexpensive and highly soluble but display restricted chiral selectivity. To overcome these limitations, this study introduces phosphated maltodextrin (PMD), a novel anionic derivative designed to enhance enantiomeric resolution through the combined influence of electrostatic and hydrophobic interactions. PMD was synthesized via a simple aqueous method and characterized by standard spectroscopic and elemental analyses. Its chiral recognition capability in CE was systematically assessed using five model drugs: tramadol, citalopram, hydroxyzine, amlodipine, and fluoxetine. Compared with native maltodextrin, PMD markedly improved enantiomeric resolution-for example, Rs increased from 0.44 to 1.33 (tramadol), 3.37 to 7.54 (citalopram), 0.58 to 1.73 (amlodipine), and 1.88 to 4.23 (hydroxyzine). These enhancements were achieved with only minor changes in migration time (-0.75 to +2.7 min across analytes). The optimized CE conditions employed a 50 mM phosphate buffer at pH 3 containing 5% (m/v) PMD, under 20 kV and 25 °C. Method validation for citalopram and hydroxyzine confirmed excellent linearity (r² > 0.983), precision (RSD < 10.2%), and accuracy (recoveries 93.09-108.56%). The method reached quantification limits as low as 10 mg/L and was successfully applied to the enantiomeric assay of commercial tablets, yielding recoveries of 97.57-102.46% of the label claim. PMD is a new anionic chiral selector combining affordability, solubility, and enhanced selectivity. Major resolution gains without longer analysis times demonstrate PMD's promising potential for routine pharmaceutical applications, with broader chiral separations to be explored in future studies.