Polarography of 3,4,5-trihydroxybenzoic acid

Polarographic oxidation of 3,4,5-trihydroxybenzoic acid on mercury and platinum electrodes is described. The electrode process is influenced by dissociation of the acid and adsorption of the oxidation products on the electrodes. The anodic peak height in differential pulse polarography is not a linear function of the concentration, which limits the determination of the acid concentration. A linear dependence of the anodic current on the concentration was found on a rotating platinum disc electrode at pH 6.5 or 2.0, which is of advantage determining the acid in physiological solutions and eluates from chromatographic columns.