WARNING
TM 5-6630-215-12
Nessler’s Reagent APHA.
Contains mercuric
compound and sodium hydroxide.
External or eye
contact:
Flush with water.
Ingestion:
give
plenty of water or milk.
Follow with citrus juice
or dilute vinegar.
Table vinegar is approximately
4% acedic acid.
Induce vomiting.
d. Nitrogen Ammonia 0-2 mg/l range (figs. 2-11 and 2-12, and para
2-18).
(1) Ammonia nitrogen is a product of the microbiological decay
of plant and animal protein.
It can be reused directly by plants and
is commonly used in commercial fertilizers.
Its presence in raw
surface waters is uncommon and indicates domestic pollution.
The
Nessler method for ammonia nitrogen testing is a sensitive, single-
reagent test, free from most common interferences.
Distillation is
not required for most samples and the Nessler reagent is stable for
over one year.
NOTE
The temperature of the demineralized water and the
water sample should be 20°
+ or -1°C (68°F)
for best results.
Higher temperature will cause
high readings and lower temperatures will cause
low results.
If the Nessler reagent becomes dark brown it
should be discarded and a fresh supply ordered.
A precipitate in the bottom of the reagent bottle
is normal.
These solids must not be disturbed in
transferring the reagent to either solution or
erratic answers may result.
The results may be expressed as mg/l ammonia (NH3)
or mg/l ammonium (NH4 ) by multiplying the mg/l
ammonia nitrogen (N) by 1.22 or by 1.29, respect-
ively.
When testing water samples containing greater
than 100 mg/l hardness (about 6 grains per
gallon) (para 2-22g) a positive interference may
result due to the precipitation of magnesium
hydroxide.
To eliminate this interference, add
one drop of Rochelle Salt reagent (6, fig. 1-5)
to the demineralized water and to the water sample
before adding the Nessler reagent in step (c).
2-45
