LaMotte SMART 2 Electronic Soil Lab - Manual (Page 68)

PROCEDURE
NOTE: Place Dispenser Cap (0692) on *Mixed Acid Reagent (V-6278). Save
this cap for refill reagents.
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 64 Nitrate-N LR)
from TESTING MENU.
5. Scroll to and select 64 Nitrate-N LR from menu.
6. Use the 1 mL pipet (0354) to add 1 mL of soil extract to a clean tube (0290)
and dilute to the line with deionized water. Cap tube and mix.
7. Insert tube into chamber, close lid and select SCAN BLANK.
8. Remove tube from colorimeter and pour off 5 mL into graduated cylinder or
similar. Discard the remaining diluted extract.
9. Pour the 5 mL diluted extract 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 10.
10. Use the 0.1 g spoon (0699) to add two measures of *Nitrate Reducing
Reagent (V-6279). Cap.
11. Hold tube by index finger and thumb and mix by inverting approximately
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.
12. At the end of the 10 minute waiting period, mix, insert tube into chamber,
close lid and select SCAN SAMPLE. Multiply the result by 100 to
determine the nitrate-nitrogen concentration in lb/acre.
13. Press OFF to turn colorimeter off or press EXIT to exit to a previous menu
or make another 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
To convert Nitrate Nitrogen (NO
3
–N) results to ppm Nitrate (NO
3
),
multiply by 4.4.
68 SMART2 SOIL MANUAL 1.07