LaMotte SMART Spectro Spectrophotometer - Manual (Page 194)

PROCEDURE
Use universal sample holder.
NOTE: Place Dispenser Cap (0692) on *Mixed Acid Reagent (V-6278). Save this
cap for refi ll 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 fi nger and thumb and mix by inverting approximately
50-60 times a minute for four minutes. Wait 10 minutes for maximum color
development.
NOTE: 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.
NOTES: 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 is obtained.
To convert Nitrate Nitrogen (NO
3
–N) results to ppm Nitrate (NO
3
), multiply by 4.4.
SMART Spectro Test Procedures 2.11 NITRATE-NITROGEN, Low Range
Test P
rocedures