Highly sensitive analysis of flavonoids by zwitterionic microemulsion electrokinetic chromatography coupled with light-emitting diode-induced fluorescence detection

A rapid zwitterionic microemulsion electrokinetic chromatography (ZI-MEEKC) approach coupled with light-emitting-diode-induced fluorescence (LED-IF, 480 nm) detection was proposed for the analysis of flavonoids. In the optimization process, we systematically investigated the separation conditions, including the surfactants, cosurfactants, pH, buffers and fluorescence parameters. It was found that the baseline separation of the seven flavonoids was obtained in less than 5 min with a running buffer consisting of 92.9% (v/v) 5 mM sodium borate, 0.6% (w/v) ZI surfactant, 0.5% (w/v) ethyl acetate and 6.0% (w/v) 1-butanol. High sensitivity was obtained by the application of LED-IF detection. The limits of detection for seven flavonoids were in the range of 3.30 × 10−8 to 2.15 × 10−6 mol L−1 without derivatization. Ultimately, the detection method was successfully applied to the analysis of flavonoids in hawthorn plant and food products with satisfactory results.