Hach DR/850 - Page 253

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Estimated Detection Limit
The estimated detection limit for programs 60 and 62 is 0.005
mg/L NO
2
-
-N. For more information on derivation and use of
Hach’s estimated detection limit, see Section 1.
Interferences
Summary of Method
Nitrite in the sample reacts with sulfanilic acid to form an
intermediate diazonium salt. This couples with chromotropic acid
to produce a pink colored complex directly proportional to the
amount of nitrite present.
Interfering
Substance
Interference Levels
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 spontane-
ously 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
NITRITE, Low Range, continued