Electrochemical behavior of kaempferol and its determination in presence of quercetin employing multi-walled carbon nanotube modified carbon paste electrode

The electrochemical behavior of kaempferol was investigated by cyclic voltammetry (CV) and square wave voltammetry (SWV) at plane and multiwalled carbon nanotubes modified carbon paste electrode (MWCNTs/CPE). Kaempferol produces an anodic peak at MWCNTs modified CPE with a quasi-reversible nature in phosphate buffer of pH 7.73. The oxidized species of kaempferol was found to be stable (Ip^a/Ip^c ≈1) over scan rates of 100∼600 mV⁻¹. The same electrode was also found to catalyze the electrode oxidation of quercetin in presence of kaempferol under similar conditions which enabled the simultaneous determination of kaempferol and quercetin. Linearity of peak currents (Ip) vs. concentrations of kaempferol and quercetin was found in the range of 6.72 × 10⁻⁹ M to 40.34 × 10⁻⁹ M with a detection limit of 2.90 × 10⁻⁹ M for kaempferol and 13.0 × 10⁻⁹ M to 50.9 × 10⁻⁹ M with a detection limit of 3.5 × 10⁻⁹ M for quercetin using fast and sensitive SWV. The developed method has been applied for the quantitative analysis of kaempferol in corms and petals of Indian traditional medicine saffron (Crocus sativus) using a phosphate buffer of pH 7.73 and the average percent recoveries obtained are 99.84 and 99.26, respectively.