Figure 3 shows the Twister spray chamber reaches 4 order of
magnitude (0.1 ppm) washout in 36 seconds whereas the Scott
spray chamber is still above 0.1 ppm at 60 seconds. The cyclonic
action of nebulizer gas in the Twister spray chamber effectively
sweeps analyte away from the nebulizer tip ensuring good
The Twister cyclonic spray chamber is a double-pass design (50
mL volume), also manufactured from high-quality borosilicate glass.
The many unique design features of the Twister design are
highlighted in Figure 1. The most important feature of the Twister is
the central transfer tube or baffle. This acts as a secondary droplet
filter to reduce the mean droplet size, which in turn reduces matrix
effects and improves precision.
Figure 1. Twister cyclonic spray chamber design features.
Precisley placed groove guarantees
Helix CT fixes nebulizer depth and
provides the optimum interface for
minimizing dead volume
UniFit connector and
with all pumped drain
Vertical wall ensures
maximum transport efficiency
Baffle cut at angle
and fused to
For ICP-OES instruments with a solid-state detector (as virtually all
are now), the most reliable figure of merit for detection limits is the
signal to root background ratio (SRBR). SRBR gives a quick, reliable
guide to the detection limits of shot noise limited elements such as
As, Pb and Se which are the hardest elements to measure by ICP.
With SRBR, the higher the value, the lower the detection limits.
Measuring detection limits with multiple solutions with large numbers
of replicates is slow with significant statistical variation.
As shown in Figure 2, the Tracey spray chamber provides the best
SRBR and hence lowest detection limits. Closely followed by the
Twister spray chamber and finally the Scott spray chamber, providing
the lowest SRBR and potentially poorest detection limit performance.
Figure 2. Signal to Root Background ratio of 5 ppm Mn for the Tracey, Twister and Scott spray
chamber with a SeaSpray nebulizer operated at 0.7 L/min nebulizer gas.
Tracey Twister Scott
Figure 3. Washout comparison of a 1000 ppm Mn in a Twister and Scott type spray chamber.
15.0 25.0 35.0 45.0 55.0 65.0 75.0 85.0
www.geicp.com Glass Expansion Newsletter | Issue 47 2