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SPRAY CHAMBER TEMPERATURE:
A CRITICAL (YET OFTEN MISSING)
PARAMETER IN ICP EXPERIMENTS
Jerry Dulude, Ron Stux, and Vesna Dolic, Glass
Expansion, [email protected]
Focus of this study on ICP-OES
 Effect of Spray Chamber Temperature on:




Analyte sensitivity
Detection limits
Matrix interferences
Plasma robustness
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Experimental
 PE 2100 Optima DV
 Power: 1450 watts
 Coolant gas: 15LPM
 Aux. gas: 0.2LPM
 Neb. Gas: 0.7LPM
 SeaSpray concentric glass nebulizer
 IsoMist Programmable Temperature spray
chamber with Twister Baffled Cyclonic
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IsoMist on Optima 2100DV
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IsoMist Characteristics
 Programmable from -10 to 60C in 1 degree
increments
 Maintains temperature to within 0.1 degree
 Built-in Peltier device
 Temperature measured near the chamber
surface
 No external plumbing
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39
6.
15
Al
3
39
4
Be .401
31
3
Cd .107
21
4.
44
Cd
0
22
6.
50
Cr
2
26
7.
71
Cr
6
20
5.
56
Cu
0
32
7.
39
Cu
3
32
4.
75
M
2
n
25
7.
61
Ni
0
23
1.
60
Ni
4
22
1.
64
Pb
8
22
0.
35
Se
3
19
6.
02
V
6
29
2.
46
Zn
4
20
6.
20
Zn
0
21
3.
85
Zn
7
20
2.
54
8
Al
Rel. DL
Effect of Temperature on Normalized
LOD (20ul/min Uptake)
12
10
8
2ml/min 21C
6
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.02ml/min 21C
.02ml/min 60C
4
2
0
PE Optima 2100DV
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39
4
Cd .40
21 1
4
Cd .44
22 0
Co 6.50
23 2
8
Cr .89
26 2
7
Cr .71
20 6
5
Cu .56
32 0
Cu 7.39
32 3
4
Fe .75
23 2
8
Ni .20
23 4
1
Ni .6 0
22 4
1
Pb .6 4
22 8
0
Se .35
19 3
6.
02
V
29 6
2
Zn .46
20 4
6
Zn .20
21 0
3
Zn .85
20 7
2.
54
8
Al
Relative Sensitivity
Effect of Temperature on Normalized
Intensity (20 uL/min)
4.00
3.50
3.00
2.50
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40C
2.00
60C
1.50
21C
1.00
0.50
0.00
PE Optima 2100DV
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Transport Efficiency vs. Uptake Rate
70%
Transport Efficiency
60%
50%
40%
30%
20%
10%
0%
0.000
0.100
0.200
0.300
0.400
0.500
0.600
Uptake mL/min
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Unexplained Intensity Enhancement
The Phenomenon
 200% enhancement at 60C
 67% possible from transport efficiency
 Where is the missing 133%?
Theories
 Higher energy plasma
 Smaller mean droplet size
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Theory of Sensitivity Enhancement
“When water is the solvent, an increase in the solvent loading
under robust conditions leads to an increase in the MgII/MgI
ratio. …the generation of hydrogen will increase locally the
thermal conductivity of the discharge.”
Todoli and Mermet, JAAS, Aug., 1998, Vol. 13, p.730
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Humidification Test
 Measure intensity in “bypass”
mode.
 Switch to humidification “ON”
mode
 Re-measure intensity without
changing conditions
Capricorn™ Argon
Humidifier
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19
.1
53
3.
96
69
31 6
C 7 .9
d
3
21 3
4.
4
C
r 2 40
67
.7
C
1
u
32 6
7
F e .3 9
23 3
M 8.20
g
28 4
M 5 .2
g
1
28 3
M 0 .2
n
7
25 1
7
Pb .61
22 0
Se 0.35
19 3
6
Z n .0 2
20 6
2
Zn .54
20 8
6
Zn .20
21 0
3.
85
7
C
a
As
Al
3
Normalised emission intensity
Effect of Humidification on Intensity
(100ul/min uptake rate)
1.05
1
0.95
0.9
without
humidifier
with humidifier
0.85
0.8
Elements
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Theory of Intensity Enhancement
Smaller Mean Droplet Size
 Initiate evaporation in the chamber
 Smaller particles reach the plasma
 More efficient atomization
 Higher intensity
 Use phase Doppler particle analyzer to
measure mean droplet size
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Sensitivity vs. Temperature
(1ml/min uptake)
Normalised emission signal
Emission intensity at different ISOMIST temperature for
Standard solution (1mg/L)
2.2
2.1
2
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.1
1
0.9
10C
15C
20C
25C
30C
Al 396.153
As 193.696
Ca 317.933
Cd 214.440
Cr 267.716
Cu 327.393
Fe 238.204
Mg 285.213
Mg 280.271
Mn 257.610
P 178.221
Pb 220.353
Se 196.026
Si 251.611
Ti 334.940
Zn 202.548
Zn 206.200
Zn 213.857
35C
ISOMIST TEMPERATURE
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Intensity and Transport Efficiency vs
Temperature
2
1.8
1.6
1.4
1.2
INTENSITY
1
Transport Eff.
0.8
0.6
0.4
0.2
0
10C
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15C
20C
25C
30C
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35C
1
Temperature vs. Robustness
(Mg+/Mg Ratio) 1ml/min uptake
Effect of temperature and Salt on Robustness
16.00
14.00
MgII/MgI Ratio
12.00
10.00
standards
8.00
salt matrix
6.00
1000ppm Na + K
500ppm Ca
4.00
2.00
0.00
10
15
20
25
30
35
Tem p C
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Temperature vs. Suppression
(1ml/min uptake)
Degree of Suppression with increasing Temp
Cd214.440
1.400
Cr267.716
Cu327.393
1.200
Fe238.204
Mg285.213
1.000
Mg280.271
0.800
Mn257.610
P178.221
0.600
Pb220.353
1000ppm Na + K
500ppm Ca
0.400
Se196.026
Si251.611
0.200
Ti334.940
Zn202.548
0.000
10C
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15C
20C
25C
30C
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35C
Zn206.200
Zn213.857
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Suppression and Intensity vs. Temperature
(average of 18 lines) 1ml/min uptake
Performance vs. Temperature
2
1.8
1.6
normalized
1.4
1.2
Intensity
1
Suppression
0.8
0.6
1000ppm Na + K
500ppm Ca
0.4
0.2
0
10C
15C
20C
25C
30C
35C
Temperature
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Summary
 Spray chamber temperature is a critical
parameter in ICP-OES experiments.
 Intensity is proportional to temperature.
 Suppression is unrelated to temperature.
 Plasma robustness increases with
temperature.
 Constant temperature is important for all
analyses.
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