On the electrochemical biosensing of phenolic compounds in wines

A simple electrochemical sensor based on polyphenol oxidases was proposed for determination of the total phenol content in wine. Application of two oxidases: tyrosinase and laccase (separately) was examined and the results were compared. An analytical characteristic of proposed sensor towards gallic acid was evaluated. The influence of sample matrix components on the sensor response was studied according to Plackett–Burman experimental design. The potential interferents ethanol, tartaric acid, sorbate, sulfate(IV), putrescine, Fe(III) and glucose, which are usually encountered in wines, were taken into account in the examination. Because of the significant matrix effect found, analyses of wine samples towards polyphenol contents were carried out using standard addition method and expressed as gallic acid equivalents. For comparative quantification of phenolic compounds well-established Folin–Ciocalteu spectrophotometric method was applied. Significant inter-method differences were observed in electrochemical behaviour of standard substance – gallic acid – and phenolic constituents of real wine samples in the presence of tartaric acid.