Determination of quercetin in the presence of tannic acid in soft drinks based on carbon nanotubes modified electrode using chemometric approaches

In the present study, determination of quercetin (QU) was studied in the presence of unexpected electroactive interference (tannic acid, TA) using electrochemical and chemometric methods. At first, the oxidation peak current of QU was optimized in the presence of TA by multivariate optimization strategy. The analysis was performed at the surface of a multi-walled carbon nanotubes modified carbon paste electrode (MWCNTs/CPE). Central composite design (CCD) and response surface methodology (RSM) were used to evaluate the effects of the four variables on the determination of QU in the presence of TA. After modification, determination of QU was investigated in the presence of TA by differential pulse voltammetry (DPV). But the two components showed intense overlapping voltammetric peaks. Therefore, it was impossible to analyze the two analytes by DPV technique. For overcoming the problem chemometric methods were assisted with voltammetric techniques. Multivariate curve resolution with alternating least squares (MCR-ALS) was applied for resolving of these voltammograms. Then, limit of detection (LOD) for QU at the present of TA was obtained 1.96 nM. The results indicated that MWCNTs/CPE could be employed for the determination of QU in presence of TA in soft drinks with satisfactory results.