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.