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Nitrogen, Total Inorganic
Sample Collection, Preservation, and Storage
Accuracy Check
Nitrogen, Total Inorganic
Page 4 of 6
Collect samples in clean plastic or glass bottles. Best results are obtained with
immediate analysis. If chlorine is known to be present, add one drop of 0.1 N
Sodium Thiosulfate (Cat. No. 323-32) for each 0.3 mg/L Cl
Preserve the sample by reducing the pH to 2 or less with concentrated (at least
2 mL) Hydrochloric Acid (Cat. No. 134-49). Store at 4 °C (39 °F) or less. Preserved
samples may be stored up to 28 days. Warm samples to room temperature.
Neutralize with 5 N Sodium Hydroxide (Cat. No. 2450-26) before analysis.
Correct the test result for volume additions. See Section 3.1.3 Correcting for Volume
Additions on page 29.
Standard Additions Method
1. After reading test results, leave the sample cell (unspiked sample) in the
instrument.
2. Touch
. Touch
Options
additions procedure will appear.
3. Touch
to accept the default values for standard concentration, sample
OK
volume, and spike volumes. Touch
are accepted, the unspiked sample reading will appear in the top row. See the
instrument manual for more information.
4. Snap the neck off a fresh HR Nitrate Nitrogen PourRite Ampule Standard,
–
500-mg/L NO
–N.
3
5. Prepare three sample spikes. Fill three mixing cylinders (Cat. No. 1896-40)
with 25 mL of sample. Use the TenSette Pipet to add 0.1 mL, 0.2 mL, and
0.3 mL of standard, respectively, to each sample and mix thoroughly.
6. Analyze each sample spike as described in the procedure above, starting with
the 0.1 mL sample spike. Accept each standard additions reading by touching
. Each addition should reflect approximately 100% recovery.
Read
7. After completing the sequence, touch
the standard additions data points, accounting for matrix interferences. Touch
, then select
View: Fit
the sample spikes and the "Ideal Line" of 100% recovery.
See Section 3.2.2 Standard Additions on page 32 for more information.
Standard Solution Method
To check accuracy, use a 10.0-mg/L Nitrate Nitrogen Standard Solution.
Alternatively, prepare this by diluting 1 mL of solution from a Nitrate Nitrogen
®
Voluette
Ampule Standard, 500-mg/L NO
The result should be 9–10 mg/L N.
. A summary of the standard
Standard Additions
to change these values. After values
Edit
Graph
and touch
Ideal Line
OK
–
–N, to 50 mL with deionized water.
3
in a one-liter sample.
2
to view the best-fit line through
to view the relationship between
NitrogenTI_TNT_Other_TTR_Eng_Ody.fm
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