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Method Performance
Summary of Method
NitrogenTI_TNT_Other_TTR_Eng_Ody.fm
The total inorganic nitrogen test is designed to provide an estimate of the total
nitrite, nitrate, and ammonia nitrogen load present in a water or wastewater
sample. This test is most applicable to the monitoring of samples taken from an
industrial process stream or a wastewater treatment stream where it is important
to track the inorganic nitrogen load as it passes through the treatment process.
The test does exhibit different recoveries of each of the three nitrogen species, as
summarized below. The test is not recommended for use when quantifying only
one of the three species. In that case, specific procedures for each particular
analyte would be more appropriate.
Species Recovery
Nitrogen Form
NH
–N
3
–
NO
–N
3
–
NO
–N
2
Precision
Standard: 20.0 mg/L NO
Program
346
See Section 3.4.3 Precision on page 44 for more information, or if the standard
concentration did not fall within the specified range.
Sensitivity
Portion of Curve
Entire range
See Section 3.4.5 Sensitivity on page 44 for more information.
Titanium (III) ions reduce nitrate and nitrite to ammonia in a basic environment.
After centrifugation to remove solids, the ammonia is combined with chlorine to
form monochloramine. Monochloramine reacts with salicylate to form
5-aminosalicylate. The 5-aminosalicylate is oxidized in the presence of a sodium
nitroprusside catalyst to form a blue colored compound. The blue color is
masked by the yellow color from the excess reagent present to give a final green
colored solution. Test results are measured at 655 nm.
Nitrogen, Total Inorganic
–
–N
3
95% Confidence Limits of Distribution
17.0–22.2 mg/L NO
∆Abs
0.010
Recovery
112%
100%
77%
–
–N
3
∆Concentration
–
0.2 mg/L NO
–N
3
Nitrogen, Total Inorganic
Page 5 of 6
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