Determination of Gallic acid by differential pulse polarography: Application to fruit juices

Phenolic compounds possess antioxidant, antitumor, antimutagenic, antibacterial and anticarcinogenic properties. Gallic acid (2,3,4-trihydroxybenzoic acid) is a natural phenolic compound; therefore, determination of trace gallic acid is very important. In this work, a novel, sensitive and reliable method was developed using differential pulse polarography. The most suitable buffer system was found to be Britton-Robinson (B-R) buffer, pH 10.0. The gallic acid peak in this medium appeared at about ?160 mV, it responded well to standard additions, and high reproducibility was obtained. The calibration graph was linear in the concentration range of gallic acid from 1.0–50.0 μM with a correlation coefficient of 0.999. The limit of detection (LOD) and limit of quantification (LOQ) were obtained as 0.3 and 1.0 μM, respectively. The proposed method was successfully applied to the determination of gallic acid in fruit juices. The influences of some other commonly found inorganic and organic salts on the determination were also examined. Some interferiences were eliminated by using complexing agents, e.g. EDTA.