Iron and sulfide will interfere by causing a
turbidity with the Nessler reagent.
interferences such as hydrazine, glycine, various
aliphatic and aromatic amines, organic chlora-
aldehydes, and alcohols may cause
greenish or other off colors or turbidity in the
(a) Measure 25 ml demineralized water by filling a clean grad-
uated cylinder to the 25 ml mark.
Pour into a clean sample cell
(b) Take a water sample by filling a second graduated cylinder
to the 25 ml mark.
Pour into another sample cell
(c) Add 1.0 ml of Nessler reagent to both sample cells by
using the 1.0 ml calibrated dropper (or 1 ml transfer pipet).
A yellow color will develop in the water sample if ammonia
nitrogen is present.
Allow at least 10 minutes for the color to
develop but do not wait more than 25 minutes before completing steps
(d) and (e).
(d) Place the sample cell containing the prepared demineral-
ized water solution into the cell holder (as a blank).
Ammonia (Nessler method) meter scale into the meter and
adjust the wavelength dial to 425 nm.
Adjust the light control for a
meter reading of zero mg/l.
(e) Replace the cell containing the prepared demineralized
water with the prepared water sample in the cell holder and read the
mg/l ammonia nitrogen (N).
e. Nitrogen, Nitrate, High range 0-30 mg/l/(figs. 2-11 and 2-12,
and para 2-18).
(1) Nitrate represents the most completely oxidized state of
nitrogen commonly found in water.
Nitrate-forming bacteria convert
nitrites into nitrates under aerobic conditions and lightning converts
large amounts of atmospheric nitrogen (N2) directly to nitrates.
Many granular commercial fertilizers contain nitrogen in the form of
(a) High levels of nitrate in water indicate biological wastes
in the final stages of stabilization or run-off from heavily fertil-
Nitrate-rich effluents discharged into receiving waters
can degrade water quality by encouraging excessive growth of algae.
Drinking waters containing excessive amounts of nitrates can cause
infant methemoglobinemia (blue babies).
For this reason, a level of
45 mg/l nitrate nitrogen has been established as the maximum allowable
concentration of nitrates in public drinking water supplies.