Detection of ammonia in near infrared region considering the effect of cross sensitivity

Most people are exposed to ammonia from inhalation of the gas or vapours. Since ammonia exists naturally and is also present in cleaning products, exposure may occur from these sources. The widespread use of ammonia on farms and in industrial and commercial locations also means that exposure can occur from an accidental release or from a deliberate terrorist attack. UV or broadband IR absorption, and Photothermal Deflection avoid the species-conversion, time delay, and adsorption problems associated with traditional sampling systems, but often use expensive, bulky or delicate radiation sources that are not suitable for commercialization. Many optical techniques also employ derivative or FM spectroscopy to increase sensitivity, but require calibration gases to provide reference signals and have complicated lineshapes due to the overlapping of multiple NH₃ absorption lines in. This is a strong indication that cross sensitivity for ammonia emission monitoring must be model.