LaMotte COD Plus Colorimeter 1922-EX2 - Manual (Page 111)

PROCEDURE
1. Press and hold ON button until colorimeter turns on.
2. Press ENTER to start.
3. Press ENTER to select TESTING MENU.
4. Select ALL TESTS (or another sequence containing 22 Potassium)
from TESTING MENU.
5. Scroll to and select 22 Potassium 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.
8. Remove tube from colorimeter. Add 4 drops of *Sodium Hydroxide, 1.0N
(4004WT). Cap and mix.
9. Use the 0.05 g spoon (0696) to add one measure of *Tetraphenylboron
Powder (6364). Cap and shake vigorously until all of the powder has
dissolved. Wait 5 minutes.
10. At end of 5 minute waiting period, mix tube again to suspend any settled
precipitate. Insert tube into chamber, close lid and select SCAN SAMPLE.
Record result.
11. Press
OFF button to turn colorimeter off or press EXIT button to exit to a
previous menu or make another menu selection.
NOTES:
l For 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.
l For the most accurate results, the sample and reagents should be at
25±4°C.
POTASSIUM 2/2 COD PLUS TEST PROCEDURES 6/02