Electrochemical Apparatus for Simultaneously Monitoring Two Gases.
U S Patent 1982 Feb;(4):
The gas monitor is capable of simultaneously determining the concentrations of two o-containing gases in an air sample. The monitor utilizes a 4-electrode potentiostat including two indicating electrodes mounted in a single electrochemical cell and immersed in an aqueous electrolyte. The air sample containing no and NO2 is passed to the first indicating electrode, where electroreduction of the NO2 produces an electric current directly proportional to the concentration. Thereafter, the gas sample is passed through an oxidizing zone between the two indicating electrodes where the original and product no are converted into NO2. Electroreduction at the second indicating electrode produces a second electric current, which is electronically processed in analog measurement circuitry to provide an indirect determination of no in the sample.
U.S. Patent No. 4,315,753, Feb. 16, 1982; Chem. Abstr. 96:40,212J