Patent ID: 8048682

Claim:
A method for selectively detecting gaseous sulfur dioxide in a SO 2 -containing sample having a temperature of at least 500° C., the method comprising: (i) providing a SO 2 -detecting device comprising an oxygen ion-conducting substrate having on its surface at least three electrodes comprising a first, second, and third electrode, the electrodes being constructed of thermally stable, electrically conductive materials and separated by a suitable space and in electrical communication by virtue of the oxygen ion-conducting substrate; (ii) driving a starting current of specified magnitude and temporal variation between the first and second electrodes; (iii) contacting the SO 2 -detecting device with the SO 2 -containing sample while maintaining the magnitude and any temporal variation of the starting current, wherein said SO 2 -containing sample causes a change in the electrical conductance of said device; and (iv) detecting said change in the electrical conductance of said device based on measuring a specified electrical property related to or indicative of the conductance of the device between the first and third electrodes, or between the second and third electrodes, and detecting SO 2 in the SO 2 -containing sample based on the measured change in electrical conductance.