Optical sensor for ammonia based on the inner filter effect of fluorescence.
A new indicator-immobilization technique for the development of a sensor material for monitoring ammonia gas in aqueous solutions in presented. It is based on the change in absorbance intensity of a lipophilized pH indicator homogeneously dissolved in silicone rubber. Exposure to ammonia leads to a deprotonation of the indicator and this increases the absorbance of the base form of the indicator bromophenol blue. The sensor responds over a 17 μg/L to 17 mg/L concentration range, with a detection limit of 12 μg/L.
Analytical Division, Institute of Organic Chemistry, Karl-Franzens University, Heinrich St. 28, A-8010, Graz, Austria.
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Wolfbeis