NEWS
Time in Sample (TIS) is the time required for the autosampler
probe to remain in the sample tube during the acquisition (Figure
3b). The TIS is based on the total read time, RPM of the peristaltic
pump (Analysis Pump Speed) and dimensions of the uptake
tubing referenced above.
If these delays could be eliminated, the analysis time per sample
could be reduced significantly and the sample throughput increased.
This is exactly what the Niagara achieves.
The Niagara begins rinsing the nebulizer and spray chamber the
instant the sample measurement is completed and continues to
rinse until the next sample is ready. Thus the rinse is carried out
in the time that is usually wasted waiting for the sample and the
rinse solutions to flow from the autosampler probe to the nebulizer.
In Figure 1 (page 1), we show a flow diagram of the Niagara in both
the “Home” and “Rinse” positions. The valve is in the “Home” position
in Figure 1a., where the sample is being directed to the nebulizer
while the rinse solution is directed to waste. At the completion of
the sample measurement, the valve switches instantly to “Rinse”
position and the rinse solution is directed to the nebulizer (Figure
1b), allowing for the nebulizer and spray chamber to begin rinsing
immediately, with no uptake delay. The valve remains in the “Rinse”
position while the autosampler probe moves to the next sample.
Only when the next sample has made its way through the full length
of the uptake tubing does the valve switch back to the “Home”
position (Figure 1a).
The typical time saved with the Niagara is around 30% and since
the valve switches immediately after the read is complete, you
also minimize the amount of sample introduced into the plasma.
This feature can drastically reduce your consumables costs,
particularly for challenging sample matrices like high TDS, HF and
organic solvents where the ICP torch and/or ICP-MS cones require
frequent cleaning and can suffer from a shorter life.
Niagara CM Rapid Rinse Updates
Since the original Niagara was introduced in January 2005,2
Glass Expansion’s line of enhanced productivity accessories has
been continuously evolving to keep up with the demands of ICP
analyses. Most recently, in 2013 we introduced the addition of a
Control Module (CM), adding the suffix CM to denote this3. With the
introduction of the CM, all Glass Expansion enhanced productivity
accessories are now controlled by a dedicated central command
unit. This provides faster and more reliable communication to the
instrument PC and an easy avenue for upgrading. Further details
on the benefits of the CM can be found in the February 2013
Newsletter.3
We are now introducing a suite of software upgrades that are
specific to the Niagara CM Rapid Rinse. Software version NRRV2
includes a redesigned Method Wizard (Figure 2), which features
an Uptake Delay Calculator, Rinse Tubing Calculator, and Time in
Sample (TIS) Calculator. The addition of these calculators greatly
simplifies method development so that you can quickly add the
Niagara to your existing ICP method and optimize for maximum
savings.
The Uptake Delay Time is the time required for the sample to reach
the valve and pass through to waste, ensuring that the first bit
of sample diluted with the previous rinse is flushed out to waste.
Once the Uptake Delay Time has finished, the Niagara valve will
switch from Rinse to the Home position, directing the sample to
the nebulizer (Figure 3a). The Uptake Delay Time is calculated
based on the ID and length of the autosampler probe; peristaltic
pump tubing ID and length; and RPM of the peristaltic pump (Fast
Pump Speed). The Rinse Tubing Calculator calculates the optimum
peristaltic pump tubing to be used in order to achieve the same
flow rate that is used during analysis while using a fast pump
during the uptake and post-acquisition rinsing steps of the analysis.
Figure 2. Niagara CM Rapid Rinse Method Wizard
Figure 3a. Niagara CM Rapid Rinse – After Uptake Delay
Niagara in Home position
after Uptake delay
Autosampler
Probe in
Sample Tube
Internal
Standard
Rinse Waste
Figure 3b. Niagara CM Rapid Rinse – During Acquisition
Niagara in Home position
during Read time
Autosampler
Probe in
Sample Tube
Internal
Standard
Rinse Waste
www.geicp.com Glass Expansion Newsletter | Issue 40 2
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