Analysis of flavonoids in propolis and Ginkgo biloba by micellar electrokinetic capillary chromatography.

A micellar electrokinetic capillary chromatography (MEKC) method has been developed for simultaneous determination of 10 bioactive flavonoids: rutin, apigenin, luteolin, eriodictyol, kaempferol, chrysin, acacetin, flavanone, flavone, and fisetin. The effect of several parameters, such as UV detection wavelength, buffer pH, buffer concentration, sodium dodecyl sulfate (SDS) concentration, beta-cyclodextrin (beta-CD) concentration, separation voltage, and injection time on the separation of these flavonoids were systematically investigated. The 10 flavonoids were successfully separated within 18 min in 20 mM Na(2)B(4)O(7)-10 mM NaH(2)PO(4) buffer (pH 9.7) containing 100 mM SDS and 16 mM beta-CD at a separation voltage of 19 kV, with UV detection at 254 nm. Regression analysis revealed a good linear relationship between the peak area of each analyte and its concentration with detection limits (S/N = 3), ranging from 0.15 to 1.36 microg mL(-1). This method could simultaneously quantify the 10 flavonoids and be used in the quality control of functional foods containing propolis and Ginkgo biloba.