engleski

Electroanalytical oxidation of p-coumaric acid

The mechanism of the electrochemical oxidation of p-coumaric acid on a glassy carbon electrode was investigated using cyclic, differential pulse and square wave voltammetry at different pHs. The oxidation of p-coumaric acid is irreversible over the whole pH range. After successive scans the p-coumaric acid oxidation product deposits on the electrode surface forming a polymeric film that undergoes reversible oxidation for a lower potential than p-coumaric acid. This polymeric film increases in thickness with the number of scans covering the electrode surface, and impeding the diffusion of the p-coumaric acid and its oxidation on the electrode surface. The oxidation of p-coumaric acid is pH dependent until values close to the pKa. For pHs higher than pKa the p-coumaric acid oxidation process was pH independent. The electroanalytical determination of p-coumaric in pH 8.7 0.2 M ammonium buffer was developed and the detection limit, LOD = 82.6 nM, and the limit of quantification, LOQ = 250 nM, were obtained.

p-coumaric acid; oxidation; radical scavenging activity; hydroxycinnamic acid; free radicals

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