Back to the Basics: Effects of Desensitizing Substances

The desensitizing effects of several substances common to industrial processes are well known. 

• For FID Analyzers: Oxygenated or halogenated compounds such as alcohols, ketones and ethers produce lowered responses due to the effect of the electronegative oxygen and halogen atoms on the production of ion current. 

• Catalytic Sensing Elements: They loose catalytic surface reactivity due to aging, the interference from absorbed silicone or organo-metallic compounds, and the corrosion produced by the acids produced as a by-product of the catalytic oxidation of halogen-bearing compounds. 

• Infrared Sensors: Even when properly compensated for reduced transmission, are responsive in general to a particular molecular bond, and thereby unsuitable for other than single-solvent systems. 

• Electrochemical and Solid-State Sensors: Even when improved, they have such an extremely wide variation in response to various solvent species, and operate at such relative low temperatures, to make their use generally impractical and unacceptable.