Electroanalytical determination of total phenolic compounds by square-wave voltammetry using a poly(vinylpyrrolidone)-modified carbon-paste electrode

• A carbon paste electrode (CPE) modified with poly(vinylpirrolidone) (PVP) was prepared.
• The calibration curve was obtained using kaempferol as a model for TPC.
• A sensor was used in the determination of total phenolic compounds (TPC) in vegetables by square-wave voltammetry (SWV).

A carbon paste electrode (CPE) modified with poly(vinylpyrrolidone) (PVP) was employed as an electrochemical sensor for the determination of total phenolic compounds (TPCs) in vegetables by square-wave voltammetry (SWV). The calibration curve obtained using kaempferol as a model for TPCs showed two linear ranges from 0.05 to 0.50 μmol L−1 (R2 = 0.980) and from 0.50 to 6.0 μmol L−1 (R2 = 0.998). With the use of the most sensitive range, the limits of detection and quantification were 40 nmol L−1 and 160 nmol L−1, respectively. The following sequence was determined for the content of TPCs in the vegetables analysed: spinach > cabbage > broccoli > chicory. The accuracy of the results provided by the proposed sensor was evaluated by comparison with the values obtained applying the Folin-Ciocalteau (FC) methodology.