Nitrogen Determination in Soils and Plants by
Flash Combustion using Argon as Carrier Gas
Liliana Krotz, Walter Galotta and Guido Giazzi
Thermo Fisher Scientific, Milan, Italy
Overview
FIGURE 1. FLASH 2000 E
Purpose: To show nitrogen determination of soils and plants by Organic Elemental
Analysis (OEA) using argon as the carrier gas.
Methods: Soils and plants were analyzed by an elemental analyzer with an automatic
autosampler, using argon as the carrier gas.
Results: Data collected of nitrogen from different soils and plants are discussed to
assess the performance of the elemental analyzer using argon as the carrier gas.
Introduction
Methods
Samples are weighed in tin
via the Thermo ScientificTM
amount of oxygen.
After combustion, the prod
reactor filled with copper, th
finally being detected by a
configuration as well as the
helium as the carrier gas (F
A complete report is autom
Xperience data handling so
The Eager Xperience softw
which allows the modificati
the analysis.
Nitrogen in soils is important for the evaluation of organic matter and the calculation of
the amount of fertilizer to be added by providing information regarding the deficiency or
excess of nutritional elements important for plant growth. Nitrogen content is important
in determining the quality of various types of crops for feeding and processing, as well
as for N-cycle and N-fixation monitoring in agricultural and environmental research.
FIGURE 2. FLASH 2000 N
For this reason the use of an accurate instrumental analytical technique is required, as
the demand for improved sample throughput, reduction of operational costs and
minimization of human errors is becoming every day more notable, it is essential to
have a simple and automatic technique which allows fast analysis with excellent
reproducibility.
The Thermo ScientificTM FLASH 2000 analyzer (Figure 1), which typically uses helium
as its carrier gas and is based on the dynamic flash combustion of the sample, copes
effortlessly with the wide array of laboratory requirements such as accuracy, day to day
reproducibility and high sample throughput. However as in recent years there have
been worldwide shortages and large increases in the cost of helium, and it has been
necessary to test an alternative gas, argon, which is readily available.
This paper presents data on nitrogen determination in soil and plant reference
materials with varying nitrogen concentrations to show the performance of the system
using argon as the carrier gas, and the reproducibility of the results obtained.
Analytical conditions
Combustion Furnace Tem
Reduction Furnace Temp
Oven Temperature:
Argon Carrier Flow:
Argon Reference Flow:
Oxygen Flow:
Sample Delay:
Run Time:
Note: The oxygen amoun
calculated automatically b
Eager Xperience software
2 Nitrogen Determination in Soils and Plants by Flash Combustion using Argon as Carrier Gas
Results
FIGURE 1. FLASH 2000 Elemental Analyzer
ants by Organic Elemental
To evaluate the performance of t
reference materials with differen
calibration was performed with a
standard using K factor as calibr
al analyzer with an automatic
nd plants are discussed to
argon as the carrier gas.
c matter and the calculation of
ion regarding the deficiency or
Nitrogen content is important
eding and processing, as well
d environmental research.
Table 1 shows the nitrogen data
Reference Material. The sample
and the accepted range accordin
The average of the 12 runs is 0.
TABLE 1. Nitrogen data of The
Weight (mg)
250.224
260.746
270.494
300.714
310.893
Methods
il and plant reference
e performance of the system
the results obtained.
270.794
280.101
290.134
After combustion, the produced gases are carried by an argon flow to a second
reactor filled with copper, then swept through CO2 and H2O traps, a GC column,
finally being detected by a thermal conductivity detector (TCD). The analytical
configuration as well as the TCD detector are the same as those used with
helium as the carrier gas (Figure 2).
A complete report is automatically generated by the Thermo ScientificTM Eager
Xperience data handling software and displayed at the end of the analysis.
The Eager Xperience software provides a new AGO (Argon Gas Option) function
which allows the modification of the argon carrier flow during the run to optimize
the analysis.
FIGURE 2. FLASH 2000 Nitrogen configuration.
300.844
320.242
350.896
Four Soil Reference Materials fr
experimental results to the expe
uncertainty. Table 3 shows the w
obtained which was very satisfa
TABLE 2. Expected N % of So
Sample Description
Low Organic Content Soil
Medium Organic Content Soil
ytical technique is required, as
of operational costs and
e notable, it is essential to
analysis with excellent
), which typically uses helium
bustion of the sample, copes
s such as accuracy, day to day
in recent years there have
st of helium, and it has been
dily available.
320.423
Samples are weighed in tin capsules and introduced into the combustion reactor
via the Thermo ScientificTM MASTM 200R autosampler together with the proper
amount of oxygen.
Loamy Soil
Chalky Soil
TABLE 3. Experimental Nitrog
Sample Description
Low Organic Content Soil
0Reference Material
Analytical conditions
Combustion Furnace Temperature:
Reduction Furnace Temperature:
Oven Temperature:
Argon Carrier Flow:
Argon Reference Flow:
Oxygen Flow:
Sample Delay:
Run Time:
950 °C
840°C
50 °C (GC column inside the oven)
60 ml/min
60 ml/min
300 ml/min
10 sec
10 min
Note: The oxygen amount necessary for the complete combustion of samples is
calculated automatically by the Thermo ScientificTM OxyTuneTM function present in the
Eager Xperience software.
Medium Organic Content Soil
0Reference Material
Loamy Soil Reference Materia
Chalky Soil Reference Materia
Thermo Scientific Poster Note • PN42209_PITTCON 2014_E_03/14S 3
Results
To evaluate the performance of the system for soil and plant analysis, relative
reference materials with different nitrogen concentrations were chosen. Instrument
calibration was performed with approximately 50 - 70 mg of Aspartic acid (10.52 %N)
standard using K factor as calibration method.
Table 1 shows the nitrogen data obtained of the analysis of Thermo ScientificTM Soil
Reference Material. The sample weight was 250 – 350 mg. The certified N % is 0.21
and the accepted range according to the technical specification is 0.19 – 0.23 N%.
The average of the 12 runs is 0.19 %N with a RSD % of 2.55.
ed into the combustion reactor
pler together with the proper
by an argon flow to a second
and H2O traps, a GC column,
ector (TCD). The analytical
same as those used with
e Thermo ScientificTM Eager
t the end of the analysis.
O (Argon Gas Option) function
ow during the run to optimize
N%
250.224
0.20
260.746
0.20
270.494
0.19
300.714
0.19
310.893
0.19
320.423
0.19
270.794
0.19
280.101
0.19
290.134
0.19
300.844
0.19
320.242
0.20
350.896
0.20
Sample
398.636
409.065
408.650
412.241
403.313
401.651
400.316
400.420
Three Plant Reference M
experimental results to th
uncertainty.
TABLE 5. Expected Nitro
Sample Description
TABLE 2. Expected N % of Soil Reference Materials.
Birch Leaves
Orchard Leaves
Alfalfa
Specification
N%
Uncertainty (±)
Low Organic Content Soil
0.133
0.023
Medium Organic Content Soil
0.27
0.02
Loamy Soil
0.27
0.02
Chalky Soil
0.35
0.02
Table 6 shows the experim
The nitrogen average of t
TABLE 6. Experimental N
Sample
50 °C
40°C
0 °C (GC column inside the oven)
0 ml/min
60 ml/min
00 ml/min
0 sec
0 min
plete combustion of samples is
TM OxyTuneTM function present in the
203.77
Weight (mg)
Experimental N %
RSD %
Low Organic Content Soil
0Reference Material
351.931
307.521
340.210
0.117
0.113
0.112
2.321
Medium Organic Content Soil
0Reference Material
285.120
336.816
322.010
0.264
0.258
0.265
1.443
Loamy Soil Reference Material
322.020
326.020
340.567
0.265
0.271
0.268
0.119
Chalky Soil Reference Material
254.416
326.987
350.471
0.337
0.365
0.372
5.173
4 Nitrogen Determination in Soils and Plants by Flash Combustion using Argon as Carrier Gas
Birch Le
Weight (mg)
TABLE 3. Experimental Nitrogen data of Soil Reference Materials.
Sample Description
Exp
Weight (mg)
402.849
Four Soil Reference Materials from 0.13 to 0.35 N % were chosen to correlate the
experimental results to the expected values. Table 2 shows the certified N % and the
uncertainty. Table 3 shows the weight of sample used and the experimental N %
obtained which was very satisfactory.
Sample Description
TABLE 4. Nitrogen data
408.698
TABLE 1. Nitrogen data of Thermo Scientific Soil Reference Material.
Weight (mg)
A Sandy Soil Reference M
method at trace level. Tab
obtained, the certified N %
The data obtained was ve
162.55
162.55
165.10
165.08
169.53
170.05
150.80
153.99
153.99
Av. N %
RSD %
and plant analysis, relative
rations were chosen. Instrument
70 mg of Aspartic acid (10.52 %N)
alysis of Thermo ScientificTM Soil
350 mg. The certified N % is 0.21
specification is 0.19 – 0.23 N%.
% of 2.55.
oil Reference Material.
N%
0.20
0.20
0.19
0.19
0.19
0.19
0.19
A Sandy Soil Reference Material at 0.07 N % (700 ppm N) was chosen to evaluate the
method at trace level. Table 4 shows the weight of sample used, the experimental N %
obtained, the certified N % and the uncertainty.
The data obtained was very satisfactory.
0.19
FIGURE 3. Typical calib
TABLE 4. Nitrogen data of Sandy Soil Reference Material.
Sample
FLASH 2000
Weight (mg)
Experimental N
%
408.698
0.0700
402.849
0.0711
398.636
0.0703
409.065
0.0707
408.650
0.0691
412.241
0.0718
403.313
0.0694
401.651
0.0692
400.316
0.0718
400.420
0.0732
Specification
RSD %
N%
Uncertainty
(±)
1.8848
0.07
0.01
Figure 4 shows a typical
Three Plant Reference Materials from 0.15 to 3.01 N % were chosen to correlate the
experimental results to the expected values. Table 5 shows the certified N % and the
uncertainty.
0.19
Figure 3 shows a typical
calibration method
FIGURE 4. Typical Nitro
0.19
0.20
TABLE 5. Expected Nitrogen values of Plant Reference Material.
0.20
Sample Description
% were chosen to correlate the
2 shows the certified N % and the
sed and the experimental N %
erials.
Specification
N%
Uncertainty (±)
133
0.023
.27
0.02
.27
0.02
.35
0.02
N%
Uncertainty (±)
Birch Leaves
2.12
0.06
Orchard Leaves
2.28
0.04
Alfalfa
3.01
0.20
Table 6 shows the experimental N% obtained which were very satisfactory.
The nitrogen average of the ten runs is inside the uncertainty.
TABLE 6. Experimental Nitrogen data.
Sample
eference Materials.
Experimental N %
RSD %
0.117
0.113
0.112
2.321
0.264
0.258
0.265
0.265
0.271
0.268
0.337
0.365
0.372
1.443
0.119
5.173
Specification
Birch Leaves
Orchard Leaves
Alfalfa
Weight (mg)
N%
Weight (mg)
N%
Weight (mg)
N%
203.77
2.11
100.46
2.24
120.889
3.06
162.55
2.12
120.53
2.24
121.957
3.07
162.55
2.11
120.21
2.26
119.196
3.09
165.10
2.13
140.23
2.30
122.920
3.04
165.08
2.12
140.32
2.25
118.133
3.03
169.53
2.14
140.34
2.28
110.219
2.99
170.05
2.13
150.60
2.31
105.062
2.97
150.80
2.11
140.39
2.26
120.706
3.08
153.99
2.11
140.20
2.30
119.268
3.09
153.99
2.11
139.63
2.29
118.429
3.05
Av. N %
2.12
2.27
3.05
RSD %
0.519
1.156
1.34
Conclusion
Good repeatability, accur
Nitrogen Analyzer using a
No memory effect was ob
complete combustion and
All trademarks are the property o
This information is not intended t
intellectual property rights of othe
Thermo Scientific Poster Note • PN42209_PITTCON 2014_E_03/14S 5
ppm N) was chosen to evaluate the
sample used, the experimental N %
Figure 3 shows a typical calibration with Aspartic acid using K factor as
calibration method
FIGURE 3. Typical calibration curve.
Material.
Specification
N%
Uncertainty
(±)
0.07
0.01
Figure 4 shows a typical nitrogen chromatogram
N % were chosen to correlate the
5 shows the certified N % and the
FIGURE 4. Typical Nitrogen chromatogram.
erence Material.
Specification
Uncertainty (±)
0.06
0.04
0.20
were very satisfactory.
ncertainty.
Leaves
Alfalfa
N%
Weight (mg)
N%
2.24
120.889
3.06
2.24
121.957
3.07
2.26
119.196
3.09
2.30
122.920
3.04
2.25
118.133
3.03
2.28
110.219
2.99
2.31
105.062
2.97
2.26
120.706
3.08
2.30
119.268
3.09
2.29
118.429
3.05
2.27
3.05
1.156
1.34
Conclusion
Good repeatability, accuracy and precision was obtained with the FLASH 2000
Nitrogen Analyzer using argon as the carrier gas.
No memory effect was observed when changing the type of sample, indicating
complete combustion and detection of the element.
All trademarks are the property of Thermo Fisher Scientific and its subsidiaries
This information is not intended to encourage use of these products in any manners that might infringe the
intellectual property rights of others.
6 Nitrogen Determination in Soils and Plants by Flash Combustion using Argon as Carrier Gas
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