Hach DR2400 - Page 450

Nitrite
Nitrite
Page 4 of 6
Nitrite_AVPP_Low_DAZ_Eng_Ody.fm
Interferences
Sample Collection, Storage, and Preservation
Collect samples in clean plastic or glass bottles. Store at 4 °C (30 °F) or lower if
the sample is to be analyzed within 24 to 48 hours. Warm to room temperature
before running the test. Do not use acid preservatives.
Accuracy Check
Standard Solution Method
Preparing nitrite standards is difficult. A standard should be prepared by a
trained chemist. Hach recommends using the standard preparation instructions
in Standard Methods for the Examination of Water and Wastewater,
Method 4500—NO
2
-B (p. 4–86 of 18th edition). Prepare a 0.150-mg/L standard.
Method Performance
Precision
Standard: 0.150 mg/L NO
2
–
–N
See Section 3.4.3 Precision on page 44 for more information, or if the standard
concentration did not fall within the specified range.
Interfering Substance Interference Levels and Treatments
Antiminous ions Interfere by causing precipitation
Auric ions Interfere by causing precipitation
Bismuth ions Interfere by causing precipitation
Chloroplatinate ions Interfere by causing precipitation
Cupric ions Cause low results
Ferric ions Interfere by causing precipitation
Ferrous ions Cause low results
Lead ions Interfere by causing precipitation
Mercurous ions Interfere by causing precipitation
Metavanadate ions Interfere by causing precipitation
Nitrate
Very high levels of nitrate (>100 mg/L nitrate as N) appear to undergo a slight amount of
reduction to nitrite, either spontaneously or during the course of the test. A small amount of
nitrite will be found at these levels.
Silver ions Interfere by causing precipitation
Strong oxidizing and
reducing substances
Interfere at all levels
Program 95% Confidence Limits of Distribution
371 0.146–0.154 mg/L NO
2
–
–N
375 0.140–0.160 mg/L NO
2
–
–N