Summary Of Method; Safety - Hach POCKET COLORIMETER II Instruction Manual

Nitrogen, Free Ammonia and Chloramine (Mono),
continued

Summary of Method

4+
Monochloramine (NH Cl) and "free ammonia" (NH and NH ) can exist in the
2 3
same water sample. Added hypochlorite combines with free ammonia to form more
monochloramine. In the presence of a cyanoferrate catalyst, monochloramine in
the sample reacts with a substituted phenol to form an intermediate monoimine
compound. The intermediate couples with excess substituted phenol to form a
green-colored indophenol, which is proportional to the amount of
monochloramine present in the sample. Free ammonia is determined by comparing
the color intensities, with and without added hypochlorite.

Safety

Good safety habits and laboratory techniques should be used throughout the
procedure. Consult the Material Safety Data Sheet (MSDS) for information specific
to the reagent used.
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