Electroanalytical Determination of Benzoic, Oxalic and Glyoxylic Acids Using Platinum Electrode

Abstract

Due to the importance of Benzoic, Oxalic and Glyoxylic acids, a voltammetric technique using platinum electrode was developed to identify the mentioned acids. The electrochemical behavior of Benzoic, Oxalic and Glyoxylic acids was studied using cyclic voltammetric technique at platinum wire electrode in sodium nitrate as a supporting electrolyte. Benzoic acid gave an oxidation peak at +0.096 V while oxalic acid showed a well single oxidation peak at +1.05 V (vs. AgǀAgCl). Glyoxalic acid showed a reduction peak in the presence of hexacynoferrite K4[Fe2(CN)6] at +0.126V. The effect of supporting electrolyte kind, pH solution, ionic strength and scan rate on the oxidation peak of Benzoic and oxalic acids or the reduction peak of glyoxylic acid were investigated. Linear sweep voltammetry was used for the electrochemical determination of these acids under the optimum experimental conditions . A concentration of 8x10-5 mol.dm-3 lower detection limit was obtained for benzoic acid and a value of 9x10-5 mol.dm-3 was detected for Oxalic and Glyoxylic acid. The effect of some metal ions, amino acids, urea and ascorbic acid as interferences was examined. The results showed that the effect ranged between -5.0 to+14.0 % on peak response. Benzoic, Oxalic and Glyoxylic acids were successfully determined in industrial waste water. Keywords: Benzoic acid, electrochemical behavior, glyoxylic acid, interferences, linear sweep, oxalic acid, platinum electrode, voltammetry.