Dyeless optical detection of ammonia in the gas phase using pH-responsive polymers with reflectometric interference spectroscopy Original Research Article

Polymers sensitive to pH were investigated to determine their potential as sensing elements for ammonia. Polymethacrylic acid and a modified polysiloxane containing carboxylic acid functions were used as sensing material for reflectometric interference spectroscopy (RIfS). A detection limit for ammonia below 200 ppb could be determined. The response of the sensor for 5 (20) ppm ammonia decreased only about 35 (28)% in synthetic air and continuous exposure to the light source within a measurement period of 68 days.