Electrochemical Sensor for the Detection of SO₂ in the Low-ppb Range

Abstract

The development of an improved electrochemical sensor for the detection of concentrations of atmospheric sulfur dioxide in the low-ppb range is described. The sensor is based on a porous Au−solid polymer electrolyte sensing electrode which is in direct contact with the gas-containing atmosphere. Although the cell design is not new, it is demonstrated that, by careful selection of component materials and experimental conditions, the determination of trace concentrations of SO2 in air is possible with detection limits of approximately 1 ppb. The use of a strong anion exchange membrane as the solid polymer electrolyte is discussed and compared with the performance of Nafion. Cross sensitivities of the sensor to the major inorganic gaseous species found in the troposphere are also presented.