®
Total/Organic Carbon and
Nitrogen in Soils
LECO Corporation; Saint Joseph, Michigan USA
Instrument: CN2000
Accessories
528-203 Combustion Boat, 502-343 Nickel Liner, HCl,
distilled H2O, hot plate, and 769-608/769-610 Halogen
Trap Materials for (non-carbonate carbon procedure),
502-029 Synthetic Carbon Standard
Calibration Standard
502-309 Soil, or other suitable standard
Sample Weight
Analysis Time
0.25 to 0.50 g
1. Prepare instrument as outlined in the operator
instruction manual (perform maintenance and leak
checks). Install 769-608 and 769-610 Halogen Trap
Materials into secondary reagent tube following the
diagram.
~5 minutes
Furnace Temperature
o
o
1350 C (reduce furnace to 1050 C when not in use)
Burn Cycle Lance Flow Purge Flow Time (sec)
1
OFF
ON
5
2
ON
ON
15
3
ON
ON
15
4
ON
ON
15
5
ON
OFF
END
Note: If the lance and purge flow rotometers are set
correctly, the time between answer printouts should be five
minutes when using the oxygen profile listed above.
Procedure for Total Carbon and Nitrogen
1. Prepare instrument as outlined in the operator
instruction manual (perform maintenance and
leak checks).
2. Analyze blanks until instrument is stable, then analyze
three to five boats containing ~1.5 g
501-427 COM-AID and three to five empty 528-203
Combustion Boats. Enter 0.2500 g as the weight. Set a
blank using results from the empty boats.
3. Weigh ~0.25 g of standard material into a 528-203
Combustion Boat and analyze three to five times, then
drift correct using these values (refer to operator’s
instruction manual for details).
4. Weigh ~0.25 g of sample into a 528-203 Combustion
Boat and analyze.
5. Analyze a standard at the end of the set to verify
calibration.
Procedure for Non-Carbonate Carbon
A weighed sample is treated with dilute acid to remove
carbonate carbon. The treated sample is analyzed to
determine the non-carbonate carbon. The difference
between the total carbon results and the acid treated
results is referred to as the carbonate carbon content.
The non-carbonate carbon results (acid treated) are
usually referred to as "Total Organic Carbon" (TOC).
2. Weigh 0.25 to 0.5 g of samples into 502-343 Nickel
Liners and record the weights (handle liners with
tongs). Also weigh ~0.25 g of 502-029 Synthetic
Carbon. The synthetic carbon standard will be used to
check the blank for this acid treatment procedure.
a. Using an eyedropper, add 1:1 (HCl:H2O by
volume) solution to samples and synthetic
carbon standard until completely wetted. Try
to use approximately the same amount of
acid on each blank and sample.
b. Place on hot plate (low setting) until dry.
Remove and cool. Wet the samples again
with diluted acid solution. If no reaction
occurs, no further acid treatment is required.
Dry on hot plate and cool.
WARNING: Use extreme caution when handling acid.
Follow all appropriate safety precautions, wear
adequate protective clothing, and handle only under a
fume hood.
3. Place 502-343 Nickel Liner into a 528-203
Combustion Boat and follow procedure below.
NOTE: Handle boats and liners with tongs. This is
especially important if carbon is <0.5%.
4. Analyze blanks until instrument is stable, then
analyze three to five combustion boats containing
nickel liners, and three to five empty combustion
boats. Enter 0.2500 g as the weight. Set a blank
using results from the empty boats.
Organic Application Note
Oxygen Profile
Typical Results for Non-Carbonate Carbon
Sample
Soil #1
Weight (g)
0.2494
0.2541
Average =
Std. Dev. =
% Carbon
6.10
6.13
6.12
0.02
Typical Results for Total Carbon/Nitrogen
Soil #2
0.3987
0.4030
0.4503
Average =
Std. Dev. =
0.80
0.78
0.78
0.79
0.01
Soil #3
0.4220
0.4141
0.3920
Average =
Std. Dev. =
0.50
0.51
0.51
0.51
0.01
Sample
Soil #1
Weight (g)
0.2780
0.3188
0.2940
Average =
Std. Dev. =
% Carbon
13.01
12.90
13.12
13.01
0.09
% Nitrogen
0.037
0.037
0.036
0.037
0.001
Soil #2
0.3978
0.3814
0.4420
Average =
Std. Dev. =
3.92
3.98
3.93
3.94
0.03
0.054
0.055
0.053
0.054
0.001
Soil #3
0.3800
0.4174
0.3849
Average =
Std. Dev. =
3.25
3.26
3.33
3.28
0.04
0.039
0.039
0.045
0.040
0.002
®
Delivering the Right Results
5. Weigh ~0.25 g of standard material into a 528-203
Combustion Boat and analyze three to five times,
then drift correct using these values (refer to
operator’s instruction manual for details).
6. Enter weight of samples from step 2 and analyze.
7. Analyze a standard at the end of the set to verify
calibration.
LECO Corporation
3000 Lakeview Avenue • St. Joseph, MI 49085 • Phone: 800-292-6141 • Fax: 269-982-8977
[email protected] • www.leco.com • ISO-9001:2000 • No. FM 24045 • LECO is a registered trademark of LECO Corporation.
Form No. 203-821-165
8/10—REV3
© 2010 LECO Corporation