Amperometric detection of polyphenols using peroxidase-immobilized gold electrodes

Horseradish peroxidase (HRP) is covalently immobilized on a self-assembled monolayer of mercaptopropionic acid on vapor-deposited gold electrode. The electrode allows the polyphenol detection down to 2 μmol dm^-3 with a linear relationship up to 25 μmol dm^-3. The reduction current of oxidized polyphenol intermediate formed during the enzymatic reaction in the presence of H₂O₂ is proportional to the concentration of polyphenol. The present method is applicable to the determination of the total polyphenol content in wine and tea.