The development of new microelectrode gas sensors: an odyssey: Part IV. O2, CO2 and N2O reduction at unshielded gold microdisc electrodes

In this work, we describe the reduction of O2, CO2 and N2O, in the presence of each other, at an unshielded gold microdisc electrode, in dimethylsulfoxide (DMSO) as the solvent and with a Ag quasi-reference electrode. Carbon dioxide and nitrous oxide, when present on their own in N2, have been shown previously to be reduced at very similar potentials. So, it was not necessarily anticipated that gas mixtures containing both these two gases could be determined analytically. However, remarkably, a well resolved new CO2 wave, which was ideal for analytical purposes, was observed under our experimental conditions in the presence of O2 and N2O. Furthermore, and most importantly, no cross-interference from the O2, N2O, and the new CO2 reactions, was evident when the N2O concentration was in excess of that of CO2 (the normal anaesthetic expired gas and blood gas analysis situation). The O2, CO2 and N2O concentrations were determined from the limiting currents of the well-separated waves.