Performance of an Inert Self-aspirating Micro flow Nebulizer

1
Performance of an Inert Self-aspirating Micro
flow Nebulizer
Salar Samii, Jonathan A. Levine, Kaveh Kahen, and
Akbar Montaser
The George Washington University Department of
Chemistry Washington, DC 20052
Jerry Dulude and Bobby Brezni
Glass Expansion Melbourne, Australia
2
Introduction
In recent years, nebulizers used in inductively
coupled plasma (ICP) spectrometry, particularly
in ICPMS, operate at lower uptake rates to
enhance the transport efficiency and to reduce
oxide formation. In this study, a new PFA
nebulizer (Glass Expansion) is examined, in
terms of droplet size and velocity distributions,
at a self-aspirating rate of 10 ml/min. The
results are compared to data obtained for several
concentric glass nebulizer.
3
Sample Introduction Components
Twister spray chamber With Helix nebulizer
fitting
Conikal AR30-1-FC2E
MicroMist AR30-1-FM005E
OpalMist AR30-1-PFA001
4
Critical Dimensions
Conikal
Capillary i.d.
Gas Orifice i.d.
Gas Annulus Area
280 mm
320 mm
12 mm
MicroMist
Gas Annulus Area
Capillary i.d.
Gas Orifice i.d.
123 mm
240 mm
16 mm
OpalMist
Capillary i.d.
Gas Orifice i.d.
Gas Annulus Area
360 mm
60 mm
55 mm
5
The Phase Doppler Particle Analyzer
Transmitting probe
Ar laser
Fiberoptics light coupler
Measurement volume
Receiver optics
Computer
PMT detectors
Measurement electronics
6
Droplet Size Distribution (Primary Aerosol)
Nebulizer Gas Flow Rate 1.0 L/Min Solution
Uptake Rate Natural Aspiration
MicroMist
100
D32 7.1
60
Normalized Count
Normalized Volume
20
OpalMist
100
D32 12.8
60
20
10
10
20
30
40
50
0
20
30
40
50
60
0
60
Diameter (mm)
Diameter (mm)
7
Droplet Size Distribution (Primary Aerosol)
Nebulizer Gas Flow Rate 0.6 L/Min Solution
Uptake Rate 80 µL/Min
MicroMist
100
D32 10.4
60
Normalized Count
Normalized Volume
20
OpalMist
100
D32 14.2
60
20
10
10
20
30
40
50
60
0
20
30
40
50
60
0
Diameter (mm)
Diameter (mm)
8
Droplet Size Distribution (Primary Aerosol)
Nebulizer Gas Flow Rate 0.2 L/Min Solution
Uptake Rate 80 µL/Min
Conikal
100
D32 27.0
60
20
MicroMist
100
D32 23.7
60
Normalized Count
Normalized Volume
20
OpalMist
100
D32 24.5
60
20
0
0
20
40
80
60
20
40
80
60
Diameter (mm)
Diameter (mm)
9
Droplet Size Distribution (Primary Aerosol)
Conikal
MicroMist
100
Nebulizer Gas Flow Rate 1.0 L/Min Uptake Rate
Natural Aspiration D32 17.2
1.0 L/Min Natural Aspiration 7.1
60
20
100
0.6 L/Min 80 µL/Min 19.2
0.6 L/Min 80 µL/Min 10.4
60
Normalized Count
Normalized Count
20
100
0.2 L/Min 80 µL/Min 27.0
0.2 L/Min 80 µL/Min 23.7
60
20
0
20
40
80
60
20
40
80
60
0
Diameter (mm)
Diameter (mm)
10
Droplet Velocity Distribution (Primary Aerosol)
Conikal
MicroMist
300
Nebulizer Gas Flow Rate 1.0 L/Min Uptake Rate
Natural Aspiration Vx 40.8 m/s
1.0 L/Min Natural Aspiration 53.9
200
100
400
0.6 L/Min 80 µL/Min 29.7
0.6 L/Min 80 µL/Min 32.7
200
Counts
0
900
0.2 L/Min 80 µL/Min 10.1
0.2 L/Min 80 µL/Min 11.6
600
300
0
0
20
40
80
60
100
120
20
40
80
60
100
120
Axial Velocity (m/s)
Axial Velocity (m/s)
11
Droplet Velocity Distribution (Primary Aerosol)
MicroMist
300
Nebulizer Gas Flow Rate 1.0 L/Min Uptake Rate
Natural Aspiration Vx 48.9 m/s
200
100
Counts
450
0.6 L/Min 80 µL/Min 29.5
300
150
20
40
80
60
0
100
120
Axial Velocity (m/s)
12
Droplet Size Distribution (Tertiary Aerosol)
Nebulizer Gas Flow Rate 1.0 L/Min Solution
Uptake Rate Natural Aspiration
Conikal
100
D32 4.9
60
20
MicroMist
100
D32 5.0
60
Normalized Count
20
OpalMist
100
D32 6.1
60
20
0
10
20
40
30
50
Diameter (mm)
13
Conclusions

1. The size and velocity of the aerosol produced by
   three Glass Expansion nebulizers were examined.
2. The results showed that the MicroMist nebulizer
   produced the finest primary aerosol with the
   smallest D32 value obtained at a gas flow rate of
   1.0 L/min.
3. The tertiary aerosol obtained at a gas flow rate
   of 1.0 L/min was generally fine for all three
   nebulizers with the Conikal nebulizer producing
   the smallest D32 values.
4. The results suggest that although the MicroMist
   nebulizer is probably the most suitable nebulizer
   (among the three) for direct injection
   nebulization in ICP, significant improvements in
   terms of aerosol size distribution must be made.