Electrochemical behavior and adsorptive stripping voltammetric determination of quercetin at multi-wall carbon nanotubes-modified paraffin-impregnated graphite disk electrode

Multi-wall carbon nanotubes-modified paraffin-impregnated graphite disk was fabricated by using choline bond and catalyzer (MWCNT/Ch/WGE), and the properties were, respectively, investigated by field emission scanning electron microscope (FE-SEM) and X-ray photoelectron spectroscopy (XPS). Electrochemical behavior of quercetin was studied in detail by FE-SEM, UV-spectroelectrochemical and various electrochemical methods, which related with the two catechol hydroxyl groups and the other three hydroxyl groups, the former is electron-donating group with a two electron two proton reversible reaction, and is pH dependent. A highly sensitive adsorptive stripping voltammetric measurement (AdSV) for quercetin was also shown at this electrode. On the optimum conditions, the adsorptive stripping response of the peak (E = 0.15 V, 3 min accumulation) was proportional to the concentration in a range of 9.0 × 10⁻⁹ to 4.0 × 10⁻⁵ M. A detection limit of 4.8 × 10⁻⁹ M was obtained with a signal-to-noise ratio (s/n) of 3 and a good precision (R.S.D.: 2.1%, n: 9). Such attractive ability of MWCNT/Ch/WGE suggests a great promise for a quercetin amperometric sensor.