LaMotte SMART Spectro Spectrophotometer - Manual (Page 174)

PROCEDURE
Use universal sample holder.
þNOTE: Place Dispenser Cap (0692) on *Mixed Acid Reagent (V-6278).
Save this cap for refill reagents.
1. Press and hold
ON button until spectrophotometer turns on.
2. Scroll to and select PROGRAMMED TESTS.
3. Scroll to and select ALL TESTS (or another sequence containing
64 Nitrate-N LR
) from TESTING MENU.
4. Scroll to and select 64 Nitrate-N LR from menu.
5. Rinse a clean tube (0290) with sample water. Fill to 10 mL line with
sample.
6. Insert tube into chamber, close lid and select SCAN BLANK.
7. Remove tube from Spectro and pour off 5 mL into graduated cylinder or
similar. Discard the remaining sample.
8. Pour the 5 mL sample from a graduated cylinder or similar into the tube.
Use the graduated cylinder or similar to measure 5 mL of *Mixed Acid
Reagent (V-6278) and add to tube. Cap and mix. Wait 2 minutes before
proceeding to Step 9.
9. Use the 0.1 g spoon (0699) to add two measures of *Nitrate Reducing
Reagent (V-6279). Cap.
10. Hold tube by index finger and thumb and mix by inverting approximately
50-60 times a minute for four minutes. Wait 10 minutes for maximum
color development.
þNOTE: At end of waiting period an undissolved portion of Nitrate
Reducing Reagent may remain in bottom of the tube without affecting
results.
11. At the end of the 10 minute waiting period, mix, insert tube into chamber,
close lid and select SCAN SAMPLE. Record result.
12. Press
OFF button to turn spectrophotometer off or press EXIT button to
exit to a previous menu or make another menu selection.
þNOTES: 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.
To convert Nitrate Nitrogen (NO
3
–N) results to ppm Nitrate (NO
3
),
multiply by 4.4.
SMART SPECTRO TEST PROCEDURES 04.08 Nitrate-Nitrogen–LR 3/3