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DR/2400
Method 10071
Test 'N Tube™ Vials
Scope and Application:
Tips and Techniques
• Digestion is required for determining total nitrogen. The digestion procedure is included below.
• Place a safety shield in front of the COD reactor to prevent injury if splattering occurs.
• This test is technique-sensitive. Invert the vials as described here to avoid low results: Hold the vial in a vertical position with the
cap pointing up. Turn the vial upside-down. Wait for all of the solution to flow down to the cap. Pause. Return the vial to an upright
position. Wait for all the solution to flow to the bottom of the vial. This process equals one inversion.
• Wipe the outside of sample cells before each insertion into the instrument cell holder. Use a damp towel followed by a dry one to
remove fingerprints or other marks.
• If the test overranges, repeat the digestion and measurement with diluted sample. The digestion must be repeated for accurate
results.
• Use the deionized water provided in the reagent set or Organic-free Water (Cat. No. 26415-49) to prepare the standards and
perform the procedure.
Test 'N Tube
1.
Turn on the COD
Reactor. Heat to
103-106 °C (optimal
temperature is 105 °C).
NitrogenTot_TNT_Other_PSD_Eng_Ody.fm
For water and wastewater
2.
Using a funnel, add
the contents of one Total
Nitrogen Persulfate
Reagent Powder Pillow
to each of two Total
Nitrogen Hydroxide
Reagent vials.
Wipe off any reagent that
may get on the lid or the
tube threads.
Nitrogen, Total
Persulfate Digestion Method
3.
Add 2 mL of sample
to a vial (this is the
prepared sample).
Add 2 mL of the deionized
water included in the kit
to a second vial (this is the
reagent blank).
Note: Use only water that is
free of all nitrogen-containing
species as a substitute for the
deionized water provided.
LR (0.5 to 25.0 mg/L N)
Method 10071
4.
Cap both vials. Shake
vigorously for at least
30 seconds to mix.
Note: The persulfate reagent
may not dissolve completely
after shaking. This will not
affect accuracy.
Nitrogen, Total
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