LaMotte COD Plus Colorimeter 1922-EX2 - Manual (Page 73)

PROCEDURE
1. Press and hold ON button until colorimeter turns on.
2. Press ENTER to start.
3. Press ENTER to select TESTING MENU.
4. Scroll to and select ALL TESTS (or another sequence containing
6 Ammonia-NH
) from TESTING MENU.
5. Scroll to and select 6 Ammonia-NH from menu.
6. Rinse a clean tube (0290) with sample water. Fill to the 10 mL line with
sample.
7. Insert tube into chamber, close lid and select SCAN BLANK. (See Note)
8. Remove tube from colorimeter. Add 8 drops of Ammonia Nitrogen
Reagent #1 (V-4797). Cap and mix. Wait 1 minute.
9. Use the 1.0 mL pipet (0354) to add 1.0 mL of *Ammonia Nitrogen
Reagent #2 (V-4798). Cap and mix. Allow 5 minutes for maximum color
development.
10. At end of the 5 minute waiting period, immediately mix, insert tube into
chamber, close lid and select SCAN SAMPLE. Record result.
11. Press OFF button to turn the colorimeter off or press the EXIT button exit
to a previous menu or make another menu selection.
CALCULATIONS:
To express results as Unionized Ammonia (NH
3
):
ppm Unionized Ammonia (NH
3
) =
ppm Ammonia-Nitrogen (NH
3
–N) x 1.2
To express results as Ionized Ammonia (NH
4
):
ppm Ionized Ammonia (NH
4
+ ) =
ppm Ammonia-Nitrogen (NH
3
–N) x 1.3
To determine the percentages of Unionized and Ionized Ammonia-Nitrogen,
consult the Appendix.
NOTE: For the best possible results, a reagent blank should be determined to
account for any contribution to the test result by the reagent system. To
determine the reagent blank, follow the above test procedure to scan a distilled
or deionized water blank. Then follow the above procedure to perform the test
on a distilled or deionized water sample. This test result is the reagent blank.
Subtract the reagent blank from all subsequent test results of unknown samples.
It is necessary to determine the reagent blank only when a new lot number of
reagents are obtained.
COD PLUS TEST PROCEDURES 2/04