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NITRATE, Low Range,
Accuracy Check
Method Performance
continued
Standard additions Method
a) Fill three 25-mL graduated mixing cylinders with 15 mL
of sample.
b) Snap the neck off a Nitrate Nitrogen Ampule Standard
Solution, 12.0 mg/L NO
c) Using the TenSette Pipet, add 0.1, 0.2, and 0.3 mL of the
standard to the three samples. Stopper and mix well.
d) Analyze each sample as described above. The nitrate
nitrogen concentration should increase 0.08 mg/L for each
0.1 mL of standard added.
e) If these increases do not occur, see Standard Additions
(Section 1) for more information.
Standard Solution Method
Prepare a 0.20 mg/L nitrate nitrogen standard by diluting 2.00 mL
of a
10.0 mg/L Nitrate Nitrogen Standard Solution to 100.0 mL with
deionized water. Use this standard in place of sample in Step 3.
Standard Adjust
To adjust the calibration curve using the reading obtained with
the 0.20-mg/L standard solution, press the
(using the arrow keys) to the STD setup option. Press
activate the standard adjust option. Then enter
standard concentration to match that of the standard used. Press
to complete the curve adjustment. If you are using a
ENTER
reagent blank correction, the blank correction should be entered
before the Standard Adjust feature is entered. See Section 1,
Standard Curve Adjustment for more information.
Precision
In a single laboratory using a standard solution of 0.25 mg/L
nitrate nitrogen (NO
with the instrument, a single operator obtained a standard
deviation of +0.03 mg/L nitrate nitrogen.
246
-
-N.
3
-
-N) and two representative lots of reagent
3
key and scroll
SETUP
to
ENTER
to edit the
0.20
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