LaMotte SMART Spectro Spectrophotometer - Manual (Page 59)

PROCEDURE–FRESH WATER
Use universal sample holder.
1. Press and hold ON button until spectrophotometer turns on.
2. Scroll to and select PROGRAMMED TESTS from menu.
3. Scroll to and select ALL TESTS (or another sequence containing
3 Ammonia-N LF
) from TESTING MENU.
4. Scroll to and select 3 Ammonia-N LF from menu.
5. Rinse a clean tube (0290) with sample water. Fill to the 10 mL line with
sample.
6. Insert tube into chamber, close lid and select SCAN BLANK. (See Note.)
7. Remove tube from Spectro. Use the 1.0 mL plastic pipet (0354) to add 2.0
mL of *Salicylate Ammonia #1 (3978). Cap and mix.
8. Use the 0.15 g spoon (0727) to add two measures of *Salicylate #2
Reagent (7457). Cap and mix until dissolved. Wait 1 minute.
9. At end of 1 minute waiting period use 0.1 g spoon (0699) to add two
measures of *Salicylate #3 Reagent Powder (7458). Cap and shake
vigorously for at least 30 seconds and all solid has dissolved. Wait 12
minutes for maximum color development.
10. At the end of 12 minute waiting period, mix, insert tube into chamber,
close lid and select SCAN SAMPLE. Record result.
11. Press OFF button to turn spectrophotometer off or press
EXIT button to
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
þNOTES: 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.
To determine the percentage of Ammonia-Nitrogen that is unionized and
ionized, consult the Appendix.
Ammonia-Nitrogen LR 2/3 SMART SPECTRO TEST PROCEDURES 05.04