Analysis Of Ten Flavonoids In Propolis And Ginkgo Biloba By Capillary Electrophoresis

A micellar electrokinetic capillary chromatography(MEKC) method has been developed for simultaneous determination of ten bioactive flavonoids:rutin,apigenin, luteolin,eriodictyol,kaempferol,chrysin,acecatin,flavanone,flavone and fisetin.Effect of several parameters,such as UV detection wavelength,buffer pH,buffer concentration, sodium dodecyl-sulphate(SDS) concentration,β-cyclodextrin(β-CD) concentration, injection time and separation voltage on separation of these flavonoids were systematically investigated.The ten flavonoids were successfully separated within 18 min in 20 mmol/L Na₂B₄O₇-10 mmol/L NaH₂PO₄ buffer(pH 9.7) containing 100 mmol/L SDS and 16 mmol/Lβ-CD at a separation voltage of 19 kV with 10 s(at 3.45 kPa) as injection time and UV detection at 250 nm.A good linear relationship between the peak area and concentration was found in the ranges of 4.5-100 mg/L,1.5-80 mg/L,0.6-80 mg/L,2.0-100 mg/L,2.3-100 mg/L,1.0-80 mg/L,1.5-100 mg/L,3.5-80 mg/L,3.5-100 mg/L and 3.5-100 mg/L for rutin,apigenin, luteolin,eriodictyol,kaempferol,chrysin,acecatin,flavanone,flavone and fisetin respectively.The detection limits(S/N=3) were 1.36,0.47,0.15,0.56,0.74,0.33,0.47,1.05,0.90 and 0.85 mg/L respectively.The developed method was applied to the analysis of selected flavonoids in propolis and Ginkgo biloba health foods,including five brands of propolis soft gels,three brands of Ginkgo biloba soft gels,Ginkgo biloba tablets and tea.It was found that rutin,apigenin, luteolin,and chrysin co-existed in the raw propolis and the five brands of propolis soft gels, and the contents of rutin,apigenin,and luteolin in the five brands were overall highest in Jin'aoli propolis soft gels.It was also observed that eriodictyol,flavanone,flavone,and fisetin were not found in raw propolis and five brands of propolis soft gels.Meanwhile, kaempferol could not be detected in Jin'aoli and Tongrentang under the current conditions, while acacetin was only detected in Tongrentang.Besides,Rutin,apigenin and luteolin were simultaneously found in the Ginkgo biloba leaves,tea,tablets,Heshi and Huana Ginkgo biloba soft gels.However,only rutin was found in Jiankangzaixian Ginkgo biloba soft gels.The method is simple,rapid and with satisfactory recoveries and good reproducibilities.It can be used to control the quality of health foods containing propolis and Ginkgo biloba.