Municipal water plants produce chloramines by adding Hypochlorous acid (HOCl) and Ammonia (NH3) to the water. When the two chemicals are added into the water a chemical reaction occurs producing the chloramine. Therefore the sensing mechanism should also be able to detect the concentration level of at least chlorine contribution from the Hypochlorous acid.
The concentrations of the different referred chloramines (mono/di/tri chloramines) are pH dependent. This means that all three chloramines are of interest since they can all be present within the feed water pH range. The sensing mechanism should be able to cope with all three.