Electrochemical Measurement of the Dissolved Oxygen Concentration in Water in the Absence of Deliberately Added Supporting Electrolyte

It is commonly assumed that the use and application of electrochemical techniques to natural surface waters requires the presence of high electrolyte concentrations prior to measurement, so limiting the applicability of the technique. We report that even for the complex case of oxygen reduction, an analytically useful electrochemical signal is obtainable using a carbon fibre microcylinder electrode. It is shown to be the case even when using voltammetric signals recorded in potable water that has not been pre‐treated or had the addition of any ionic material. The magnitude of the redox wave gives a reliable measure of the oxygen content of these solutions which contain only few millimolar of ions and contains no pH buffer.