A ratiometric fluorescence sensor for the detection of ammonia in water

The shift in the fluorescence emission spectrum of oxazine 170 perchlorate (O17) when being deprotonated and bound with ammonium ions in water was exploited to fabricate a ratiometric ammonia sensor. The ratiometric fluorescence sensing was performed by using the ratio of the fluorescence intensities of two emission wavelengths at λem = 565 nm and λem = 630 nm. Ethyl cellulose (EC) was combined with the O17 to allow for the configuration of a thin membrane for the convenient detection of ammonia in water. Good compatibility of the O17 and EC has produced a successful ammonia-sensing membrane for use in the NH3 range of 1–60 ppm with a short response time (t95 = 10 s), high reversibility, less interference, and long-term stability. The ammonia-sensing membrane (O17-EC membrane) was applied for the determination of ammonia in artificial waste water containing different ions. The results obtained were in good agreement with the concentrations of ammonia added to the artificial waste water samples.