Online Enrichment and Separation of Phthalides and Phenolic Acids From Chuanxiong Rhizoma by Reversed Migration Cyclodextrin-Modified Micellar Electrokinetic Chromatography Combined With a Three-Step Enrichment Technique.

A sensitive three-step online enrichment strategy including large-volume sample stacking, dynamic pH junction, and sweeping was successfully developed and validated for the simultaneous online enrichment and separation of phthalides and phenolic acids in Chuanxiong Rhizoma (CX) by coupling reversed migration cyclodextrin-modified micellar electrokinetic chromatography (RM-CD-MEKC) with a diode array detector. The samples were prepared in a low-conductivity, high-pH matrix consisting of 3 mM borax buffer at pH 7.5. The background electrolyte was a high-conductivity, low-pH buffer containing 10 mg·mL-1 sulfobutylether-β-cyclodextrin, 80 mM sodium dodecyl sulfate, and 25 mM sodium dihydrogen phosphate in 20% methanol (pH 3.5). Under the optimized conditions, four major active components (senkyunolide A, senkyunolide I, ferulic acid, and chlorogenic acid) of Ligusticum chuanxiong Hort. were efficiently separated within 17 min, achieving good resolution and 10- to 44-fold enrichment. The limits of detection ranged from 0.09 to 0.25 µg·mL-1 while the limits of quantification ranged from 0.31 to 2.24 µg·mL-1. The relative standard deviations for intra-day and inter-day precision were all below 3.45%, demonstrating good precision and method stability. Overall, the proposed RM-CD-MEKC combined with a three-step enrichment technique provides a simple, rapid, and environmentally friendly enrichment approach for the simultaneous determination of phthalides and phenolic acids in CX samples.