Optical sensor for ammonia based on polyaniline

Polyaniline was immobilized on an acetate film and configured to fit into a window of a sample cell. The system showed a stable response at 600 nm where absorbance readings were done giving a response time of 1.2 minutes. It showed good reproducibility, with a relative standard deviation of 1%. Ammonia gas samples were collected from the head space of aqueous ammonia solutions and fed into the sample cell. These were tested in the sample cell and showed linear response with an equation: y = 0.0139x - 0.0977, and a linearity of 0.9317. Its calculated limit of detection is 2.16. These figures of merit show the potential of a simple sensor based on polyaniline using the acetate as a support matrix.