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Nitrogen, Total
Interferences
Nitrogen, Total
Page 4 of 8
The substances in Table 1 have been tested and found not to interfere up to the
indicated levels (in mg/L). Interfering substances the resulted in a concentration
change of ±10% appear in Table 2.
Table 1 Non-interfering Substances
Substance
Barium
Calcium
3+
Chromium (
)
Iron
Lead
Magnesium
Organic Carbon
pH
Phosphorus
Silica
Silver
Tin
Substance
Bromide
Chloride
Hach chemists tested this chemistry on standard nitrogen solutions prepared
from the following compounds and obtained 95% recovery:
• Ammonium chloride
• Ammonium sulfate
• Ammonium acetate
Ammonium chloride or nicotinic-PTSA spikes in domestic influent, effluent and
the ASTM standard specification for substitute wastewater (D 5905-96) also
resulted in ≥ 95% recovery.
The large amounts of nitrogen-free organic compounds in some samples may
decrease digestion efficiency by consuming some of the persulfate present.
Samples known to contain high levels of organics should be diluted and re-run
to verify digestion efficiency.
Maximum Level Tested
Table 2 Interfering Substances
Level and Effect
> 60 mg/L; positive interference
> 1000 mg/L; positive interference
• Urea
• Glycine
2.6 mg/L
300 mg/L
0.5 mg/L
2 mg/L
6.6 µg/L
500 mg/L
150 mg/L
13 pH units
100 mg/L
150 mg/L
0.9 mg/L
1.5 mg/L
NitrogenTot_TNT_Other_PSD_Eng_Ody.fm
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