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Approaching a Universal Pneumatic Nebulizer Jerry
Dulude (USA), Vesna Dolic and Peter Liddell
(Australia), Glass Expansion (www.geicp.com)
PE OPTIMA 2100DV ICP-OES
VARIAN VISTA MPX AXIAL ICP-OES
INTRODUCTION
Glass Expansion currently designs nebulizers to
accommodate the recommended gas pressures and
flows of the various spectrometer manufacturers.
However, it is desirable to design a single
nebulizer that when run under high pressure
conditions will generate a finer mist and more of
it. In this study a nebulizer was designed to
operate at 60psi, markedly higher than that of a
standard nebulizer. This nebulizer was compared
to the standard for a variety of performance
parameters on two different ICP-OES systems.
Figure 9 Effect of Pressure on Performance-
Long-term Stability (2ml/min uptake)
Inter-Nebulizer Variation
Figure 4 Effect of Pressure on Performance-
Short-term Stability (2ml/min uptake)
Figure 7 Effect of Pressure on Performance
Signal Intensity (2ml/min uptake)
To determine the effects of subtle changes in
parameters, it is necessary to first establish
the inter-nebulizer variability within a given
design. Figure 2 demonstrates the inter-nebulizer
variability for a group of 5 different 60 psi
nebulizers of the same configuration at two
different uptake rates. Note that even though the
uptake rate has been decreased by a factor of 5,
emission intensity counts are decreased by only
about 20 to 25. This is due to the much higher
efficiency produced at lower uptake rates.
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60psi
30psi
60psi
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60psi
EXPERIMENTAL
Figure 10 Effect of Pressure on Performance-
Detection Limit (2ml/min uptake)
Figure 8 Effect of Pressure on Performance-
Short-term Stability (0.4ml/min uptake)
Figure 5 Effect of Pressure on Performance-
Long-term Stability (2ml/min uptake)
Figure 2 Inter-Nebulizer Study Results (60psi)
A Tracey Cyclonic spray chamber was used with a
SeaSpray concentric glass nebulizer (both from
Glass Expansion, Inc., Pocasset, MA and shown
below in Figure 1). Standard conditions were
used across the board on both a Varian Vista MPX
and a Perkin Elmer Optima 2100. Both ICP-OES
instruments were used with axial view for all
lines.
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60psi
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60psi
Figure 1 Sample Intro System
DISCUSSION and
CONCLUSIONS
Figure 6 Effect of Pressure on Performance-
Detection Limit (0.4ml/min)
Figure 3 Effect of Pressure on Performance
Signal Intensity (2ml/min uptake)
Figure 2 illustrates that the high
reproducibility of various nebulizers of the same
design enables detection of differences between
nebulizers of a different design. Figures 3
through 6 show the improvements provided by the
60psi design in terms of intensity, stability,
and detection limit for the Varian Vista MPX.
This improvement is duplicated for the same
parameters on the Perkin Elmer 2100 (Figures 7
through 10). Although all studies were
conducted at both 0.4 and 2.0ml/min uptake rates,
a clear difference was not always revealed for
both. Therefore, in some cases, data is shown
for one or the other. We are currently Investigat
ing further to determine the source of these
anomalies.
A pneumatic nebulizer operated at 60psi offers
significant improvements in perfor- mance over
the standard nebulizer for two different ICP-OES
manufacturers and models. Future work will
center on the improvement in performance at
lower uptake rates and the ability of
these nebulizers to handle high dissolved
solids samples.
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60psi