Separation and determination of alpinetin and cardamonin by reverse micelle electrokinetic capillary chromatography

A novel electokinetic capillary chromatography method, reverse sodium dodecyl sulfate (SDS) micelles as pseudo-stationary phase, was developed for separation and detection of alpinetin and cardamonin. In this work, reverse micelles (RMs) have been firstly introduced into background electrolyte for electrophoresis separation. The optimum reverse SDS micelle system was formed with n-butyl chloride as continuous phase, SDS (20.9%, w/v) as the surfactant, W0 (13.0, water–surfactant molar ratio), 18.0% (v/v) 1-butanol as the co-surfactant, 8.0% (v/v) acetonitrile (ACN), 1.5% (v/v) heptane, and a 60 mol L−1 tris-(hydroxymethyl)aminomethane (Tris) buffer, as dispersed phase. Linear relationships (correlation coefficients: 0.9961 for cardamonin and 0.9991 for alpinetin) between the peak areas and concentration of the two compounds were obtained (5.0–350.0 μg mL−1 for cardamonin and 1.25–350.0 μg mL−1 for alpinetin). The detection limits (S/N = 3) for cardamonin and alpinetin were 0.19 and 0.14 μg mL−1, respectively. The method was successfully applied for the quantification of alpinetin and cardamonin in Alpinia katsumadai Hayata and kuaiwei tablet with satisfactory recoveries in the range of 95.9–100.2%.