A KINETIC SPECTROPHOTOMETRIC METHOD FOR DETERMINATION OF GALLIC ACID IN WINES

A rapid, relatively sensitive, and low-cost method for the determination of gallic acid content in wines is proposed. The method is based on the reaction of gallic acid by hydrogen peroxide in phosphate buffer (pH 7.25), in the presence of Cu(II), which acts as a catalyst. The reaction was monitored spectrophotometrically by measuring the absorbance of formed product at 405 nm. The optimum conditions regarding concentration of reagents, pH and temperature were established. The calibration curve was linear from 1.84 to 9.0 mu g ml(-1) of gallic acid and the limit of detection (3 s/S) is 0.2 mu g ml(-1) and limit of quantification (10 s/S) was 0.66 mu g ml(-1). The proposed kinetic procedure was successfully applied to monitoring of the concentration of gallic acid in wine samples from Serbia. Results obtained by the proposed kinetic procedure were compared by those obtained by HPLC method, and shown good agreement.