Effect of Surfactants and Related Biological Active Substances on the O2/H2O2 Voltammetry and Its Utilization for Determination of the Total Surfactant Content

Abstract

The effect of surfactants on the second voltammetric reduction peak of air oxygen dissolved in aqueous electrolyte solutions is described. Sodium dodecylbenzenesulfonate (DBSNa) was used as a model surfactant in the concentration range 9 × 10 ¹8 -9 × 10 ¹7 mol L ¹1 . With increasing DBSNa concentration the second oxygen reduction peak increases and shifts to negative potentials. Measurements were carried out in pure 0.1 mol L ¹1 KCl as well as in freshly collected samples of seawater. By means of calibration plots obtained with DBSNa we could determine the total surfactant concentration in seawater, i.e., the voltammetric surfactant background signal. Expressed in equivalent concentration of DBSNa this background amounted to 3 × 10 ¹7 mol L ¹1 .