Chemical sensors sulfur dioxide

A new solid state chemical sensor for sulfur dioxide utilizing a sodium sulfate/rare earth sulfates/silicon dioxide electrolyte has been developed. The addition of rare earth sulfates and silicon dioxide to the sodium sulfate electrolyte was found to enhance the durability and electrical conductivity of the electrolyte. The electrolyte exhibits a Nernstian response in the range of SC gas concentrations from 30 ppm to 1 %. 

Other methods of quantitative analysis, which are much more accurate and applicable to wider ranges of mixtures, include GC, mass spectrometry (MS), the GC-MS combination, in which products separated by GC are detected by MS, infrared spectroscopy, specific sensors to measure water, sulfur dioxide, etc., and all other appropriate techniques, which may include wet chemical analytical methods. 

Combined electrodes have been developed to measure dissolved gases such as carbon dioxide (CO2), ammonia (NH3) and sulfur dioxide (SO2). These chemical sensors contain an internal solution that is isolated from the sample solution by an hydrophobic membrane which is permeable to dissolved gas molecules... 

Multimembrane systems are another type of potentiometric sensor based on ISEs, wherein the ISE response is modified by an additional membrane of a different function. To this group of sensors belong gas-sensitive electrodes, with a hydrophobic membrane isolating the analyte firom the complex sample medium. The chemical reaction of the gaseous analyte with a component of the solution surrounding the ISE membrane proper directly produces the species to be sensed by the electrode. In food analysis, electrodes used for sulfur dioxide or ammonia belong to this group of sensors. 

Shiokawa, 1985b, J. Electrochan. Soc. 132,2519. Imanaka, N., G. Adachi and J. Shiokawa, 1986a, A solid electrolyte for sulfur dioxide detection, sodium sulfate mixed with rare earth sulfates and silicon dioxide, ACS Symposium on Chemical Sensors -Fundamentals and Applications (American Chemical Society) p. 121. 

Imanaka present, in the latter chapter, an account of the use of the rare earths to satisfy the growing demand for chemical sensors for a wide variety of substanees found in our environment that require monitoring. These include oxygen, fluorine, sulfur dioxide, earbon dioxide, moisture, alcohol, and nitric oxide. 

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