Nitrogen, Total
Nitrogen, Total
Page 4 of 8
NitrogenTot_TNT_Other_PSD_Eng_Ody.fm
Interferences
The substances in Tab le 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 Tab le 2.
Hach chemists tested this chemistry on standard nitrogen solutions prepared
from the following compounds and obtained 95% recovery:
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.
Table 1 Non-interfering Substances
Substance Maximum Level Tested
Barium 2.6 mg/L
Calcium 300 mg/L
Chromium (
3+
) 0.5 mg/L
Iron 2 mg/L
Lead 6.6 µg/L
Magnesium 500 mg/L
Organic Carbon 150 mg/L
pH 13 pH units
Phosphorus 100 mg/L
Silica 150 mg/L
Silver 0.9 mg/L
Tin 1.5 mg/L
Table 2 Interfering Substances
Substance Level and Effect
Bromide > 60 mg/L; positive interference
Chloride > 1000 mg/L; positive interference
• Ammonium chloride • Urea
• Ammonium sulfate • Glycine
• Ammonium acetate
To Next Page
Loading...
