Real-time advanced spectroscopic monitoring of Ammonia concentration in water

A direct method for real-time monitoring of Ammonia (NH₃) concentration in fish ponds is demonstrated in this study. The method is based on monitoring the spectral signature of pure NH₃ in the mid and far infrared (MIR and FIR, respectively) spectrum. A vacuum pump was used to evaporate the pond water. The evaporated water was transferred to a special gas cell for spectroscopic measurement. A linear relationship between NH₃ concentration during the evaporation process and the detected signal was found. NH₃ concentrations in the order of 1 PPM were detected with excellent agreement (<± 5%) to conventional methods. Further improvement model can be achieved if longer interaction paths are used. The advantages of the presented method are: direct measurement of NH₃ rather than the indirect calculations and measurements currently used. Better accuracy, and real-time operation is achieved with no maintenance required. The disadvantages of the suggested method are: need for calibration and minor complexity with the vacuum unit.