Nafion-MWCNT composite modified graphite paste for the analysis of quercetin in fruits of Acanthopanax sessiliflorus

The Nafion multi-walled carbon nanotube composite modified graphite paste electrode (Nafion/MWCNT-GPE) was investigated for electrocatalytic oxidation of quercetin in 0.1 mol L−1 citric–NaOH buffer (pH = 3.7) and in 20% methanol solution. This was performed by cyclic voltammetry, electrochemical impedance spectrometry (EIS) and square-wave anodic stripping voltammetry (SWASV) techniques. Quercetin shows a reversible electron transfer at the modified electrode in potential range of −0.1 V to 0.6 V. Results indicated that the electrode process was diffusion limiting. The optimum parameters for SWASV deposition condition were purging time 4 min, deposition time 150 s, deposition potential 0.0 V, pulse amplitude 40 mV, step potential 6 mV and frequency 50 Hz. At optimal conditions, the content of quercetin was found to be 2.89 mg g−1 and 4.21 mg g−1 in dry and frozen fruits of Acanthopanax sessiliflorus (A. sessiliflorus) respectively with recoveries on the quercetin in dry 99.4% and frozen 99.2% (n = 5). The SWASV method with the Nafion/MWCNT-GPE is proven to be a viable technique for determining quercetin in fruits of A. sessiliflorus samples.