Simultaneous electrochemical determination of oxygen and carbon dioxide gas mixtures in a non-aqueous solvent using unshielded and membrane shielded gold microelectrodes

The simultaneous electrochemical reduction of oxygen and carbon dioxide was investigated at a commercially available Au microelectrodes (5.0 μm, diameter) in Dimethyl Sulfoxide (DMSO) solvent, using both voltammetric and potential step chronoamperometric techniques. eement with previous voltammetric studies, carbon dioxide is shown to react with the superoxide anion radical, formed from the electro-reduction of oxygen (−1.2 V versus Ag). This cross-interference reaction complicates the simultaneous detection of oxygen and carbon dioxide. In addition, the simultaneous electro-reduction of oxygen and carbon dioxide (−2.2 V versus Ag) also presents detection difficulties, particularly at low levels of carbon dioxide. trast, the use of potential step, chronoamperometric techniques are shown to effectively collapse the deleterious cross-interference reaction between superoxide and carbon dioxide (current enhancement <2%). Furthermore, the concomitant electro-reduction of oxygen and carbon dioxide reveals a linear dependence of the transientʹs current with oxygen and carbon dioxide over a prescribed gas concentration range for both species. ition a prototype practical sensor that incorporates a polytetrafluoroethylene (PTFE, Teflon®) membrane-covered gold microelectrode, for the simultaneous measurement of oxygen and carbon dioxide over a wide concentration range, is described.