The development of new microelectrode gas sensors: an odyssey Part IV. O-2, CO2 and N2O reduction at unshielded gold microdisc electrodes

In this work, we describe the reduction of O-2, CO2 and N2O, in the presenc e of each other, at an unshielded gold microdisc electrode, in dimethylsulf oxide (DMSO) as the solvent and with a Ag quasi-reference electrode. Carbon dioxide and nitrous oxide, when present on their own in N-2, have been sho wn previously to be reduced at very similar potentials. So, it was not nece ssarily anticipated that gas mixtures containing both these two gases could be determined analytically. However, remarkably, a well resolved new CO, w ave, which was ideal for analytical purposes, was observed under our experi mental conditions in the presence of O-2 and N2O. Furthermore, and most imp ortantly, no cross-interference from the O-2, N2O, and the new CO2 reaction s, was evident when the N,O concentration was in excess of that of CO2 (the normal anaesthetic expired gas and blood gas analysis situation). The O-2, CO2 and N2O concentrations were determined from the limiting currents of t he well-separated waves. (C) 2000 Elsevier Science S.A. All rights reserved .