Study On The Electrochemical Behavior And The Detection Of Flavonoids

Chapter 1:In this chapter, the analytical methods and pharmacological of isoquercitrin, daidzein and baicalin were reviewed briefly, and the electrochemical detection methods of them were focused on.Chapter 2:In this chapter, a differential pulse voltammertry (DPV) method for determination of isoquercitrin (IQ) has been established. A stable and sensitive DPV peak has been obtained at 0.525V (vs. SCE) in Britton-Robinson buffer solution (pH=1.81). Linear relationship was held between the peak current and the concentration of isoquercitrin in the range from 3×10-7 mol·L-1 to 2×10-5 mol·L-1. The detection limit was 1×10-7 mol·L-1, the RSD was 4.8%(n=10) and the mean recovery of isoquercitrin was 98.2%-106%. The interference was determined. This method was anticipated to use in the quantitative analysis of isoquercitrin. The mechanism of electrode reaction was preliminarily discussed.Chapter 3:In this chapter, graphene was synthesized by chemical reduction method, and graphene/glassy carbon electrode was prepared. A DPV method for determination of isoquercitrin (IQ) at graphene/glassy carbon electrode has been established. A stable and sensitive DPV peak has been obtained at 0.296V (vs. SCE) in Britton-Robinson buffer solution (pH6.52). Linear relationship was held between the peak current and the concentration of isoquercitrin in the range from 5×10-8 mol·L-1～3×10-5 mol·L-1 and the detection limit was 1.7×10-8 mol·L-1. The RSD was 3.1%(n=10) and the mean recovery of isoquercitrin was 96.9%-105.0%. The interference was determined. The modified electrode has been used to determine IQ in real samples with satisfactory results. The reaction mechanism of IQ on the modified electrode was preliminarily discussed. Chapter 4:In this chapter, a DPV method for determination of daidzein (DD) has been established. A stable and sensitive DPV peak has been obtained at 0.468V (vs. SCE) in Britton-Robinson buffer solution (pH6.53). Linear relationship was held between the peak current and the concentration of isoquercitrin in the range from 2×10-6 mol·L-1 to 2.4×10-5 mol·L-1 and the detection limit was 7×10-7 mol·L-1. The RSD was 4.4%(n=5) and the mean recovery of daidzein was 97.8%-104.6%. The interference was determined. The modified electrode has been used to determine DD in real samples with satisfactory results. The reaction mechanism of DD on the modified electrode was preliminarily discussed.Chapter 5:In this chapter, a DPV method for determination of baicalin (BAI) has been established. A stable and sensitive DPV peak has been obtained at 0.468V (vs. SCE) in Britton-Robinson buffer solution (pH6.53). Linear relationship was held between the peak current and the concentration of isoquercitrin in the range from 4×10-7 mol·L-1 to 5×10-5 mol·L-1 mol·L-1 and the detection limit was 1.3×10-7 mol·L-1, RSD4.0%. (n=5), and the mean recovery of baicalin was 97.2%-103.7%. The interference was determined. The modified electrode has been used to determine BAI in real samples with satisfactory results. The reaction mechanism of BAI on the modified electrode was preliminarily discussed.