Nitrogen, Ammonia
Nitrogen, Ammonia
Page 2 of 4
NitrogenAmm_PP_Other_SAL_Eng_Ody.fm
Interferences
Sample Collection, Storage, and Preservation
Collect samples in clean plastic or glass bottles. Most reliable results are obtained
when samples are analyzed as soon as possible after collection.
If chlorine is known to be present, the sample must be treated immediately with
sodium thiosulfate. Add one drop of Sodium Thiosulfate Standard Solution,
0.1 N (Cat. No. 323-32), for each 0.3 mg of chlorine present in a one-liter sample.
9. Touch Zero.
The display will show:
0.00 mg/L NH
3
–N
10. Wipe the sample and
place it into the cell
holder.
11. Touch Read.
Results will appear in
mg/L NH
3
–N.
Interfering Substance Interference Levels and Treatments
Calcium Greater than 1000 mg/L as CaCO
3
Iron
All levels. Correct for iron interference as follows:
1. Determine the amount of iron present in the sample by following one of the Iron, Total,
procedures.
2. Add the same iron concentration to the ammonia-free water in step 3. The interference will be
successfully blanked out.
Magnesium Greater than 6000 mg/L as CaCO
3
Nitrate Greater than 100 mg/L as NO
3
–
–N
Nitrite Greater than 12 mg/L as NO
2
–
–N
Phosphate Greater than 100 mg/L as PO
4
3–
–P
Sulfate Greater than 300 mg/L as SO
4
2–
Sulfide
Sulfide will intensify the color. Eliminate sulfide interference as follows:
1. Measure about 350 mL of sample in a 500-mL Erlenmeyer flask (Cat. No. 505-49).
2. Add the contents of one Sulfide Inhibitor Reagent Powder Pillow (Cat. No. 2418-99).
Swirl to mix.
3. Filter the sample through a Folded Filter Paper (Cat. No. 1894-57) and Filter Funnel
(Cat. No. 1083-67).
4. Use the filtered solution in step 3.
Other Substances
Less common interferences such as hydrazine and glycine will cause intensified colors in the
prepared sample. Turbidity and color will give erroneous high values. Samples with severe
interferences require distillation. Hach recommends the distillation procedure using the Hach
General Purpose Distillation Set (Cat. No. 22653-00).
Zero
10 mL
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