From charge dependence to host-guest recognition: A reliable CZE method for simultaneous separation and determination of flavonoid glycosides with similar structures

Simultaneous separation of structurally similar flavonoid glycosides remains challenging in functional food analysis. This study investigated the migration behavior of eight flavonoid glycosides by capillary zone electrophoresis with UV detection (CZE-UV). Phenolic deprotonation governed effective charge and electrophoretic mobility. However, strong pH dependence reduced robustness, prompting the exploration of less charge-dependent strategies. Deep eutectic solvents (DESs) provided limited improvement, whereas methyl-β-cyclodextrin (Me-β-CD) enabled stereoselective host-guest recognition and separated all eight analytes within 12 min under optimized conditions (5.0 mM Me-β-CD). The method showed good linearity and an LOD of approximately 0.3 μg/mL, supporting its use in quality control of purified moringa leaf extracts and related functional food materials. It quantified isoquercitrin and hyperoside as major flavonoid glycosides and detected two trace peaks tentatively assigned to spiraeoside and isovitexin with LC-MS/MS support. Download: Download high-res image (170KB) Download: Download full-size image