VOLTAMMETRIC DETERMINATION AT PLATINUM MICROELECTRODES OF WATER IN ACETONE-BASED SOLUTIONS WITH LITTLE SUPPORTING ELECTROLYTE

Using three Pt electrodes including a Pt disc microelectrode as indicator electrode, water gives well defined anodic voltammetric waves in acetone. The height of the water wave is linearly proportional to the water concentration. The wave is located at about +3.0 V versus the Pt quasi-reference electrode. As perchlorate ion is oxidized in the same potential range, it is necessary to control strictly the concentration of the supporting electrolyte (LiClO4) in the determination of water. As little as 0.1 mmol l(-1) of the supporting electrolyte provides measurable waves. Voltammetry is shown to be a suitable method for determining water in acetone from millimolar to molar concentrations, and water in various substances that can be dissolved in acetone such as fats or insoluble substances such as salts. The method might be particularly useful for the in situ determination of water during voltammetric experiments in acetone.