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 indica tor electrode, water gives well defined anodic voltammetric waves in a cetone. The height of the water wave is linearly proportional to the w ater 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 me asurable waves. Voltammetry is shown to be a suitable method for deter mining water in acetone from millimolar to molar concentrations, and w ater in various substances that can be dissolved in acetone such as fa ts or insoluble substances such as salts. The method might be particul arly useful for the in situ determination of water during voltammetric experiments in acetone.