Vapochromic ammonia and moisture sensors for process monitoring

Most commercially available ammonia and moisture sensors rely on electrolytic permeable polymers for detection. These permeable polymers suffer from the lack of resolving power to differentiate between ammonia and moisture and rely on electrolytic measurements in a potentially explosive (> 4% H ₂) environment. To overcome these limitations, researchers at the Savannah River Technology Center collaborated with researchers at the University of Minnesota and the Center for Process Analytical Chemistry to employ fluorescence emission from inorganic complexes (vapochromes) to detect both vapor phase moisture and ammonia. These vapochromic crystals showed signature shifts in the fluorescence maximum after sorption of various gas phase analytes. The results from evaluating vapochromic compounds in the presence of ammonia and moisture and testing under process conditions were discussed. This is an abstract of a paper presented at the 227th ACS National Meeting (Anaheim, CA 3/28/2004-4/1/2004).