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Techniques for Increasing Productivity in ICP
Spectrometry Jerry Dulude, Glass Expansion, Inc.,
4 Barlows Landing Rd., Pocasset, MA 02559
Niagara Rapid Rinse Accessory
BACKGROUND
Effect of Sample Introduction Components
Software Approaches
The Niagara Rapid Rinse Accessory significantly
shortens the analysis cycle time of an unattended
ICP spectrometer run and as a result achieves
higher productivity and faster sample turnaround
times. The Niagara begins the rinsing of 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 to the
nebulizer. The Niagara replaces steps 5 and 6
with step 7. The Niagara is controlled by
built-in firmware and is triggered by the
autosampler. Each kit includes an autosampler
kit which has been designed for each of the major
autosampler models.
As both ICP-AES and ICP-MS spectrometers become
more and more an integral part of the production
laboratory, the emphasis on productivity is
enhanced. This paper will examine a number of
ways in which the length of the analytical cycle
can be reduced without jeopardizing the quality
of the results. These include the selection of
the ICP-AES configuration, choice of sample
introduction components, and software and
hardware approaches for shortening or eliminating
the rinse step.
Decreasing Dead Volume
Fast Pump during Rinse (stages 2, 6, and 7)

• Double pump speed during the rinse step.
• Pump stays in fast mode until the next sample is
  ready.
• Must add 10 to 15 sec. of equilibration time
  prior to integration.
• Reduces cycle time by 5 to 10

INTRODUCTION
    B Fe Zn Se Mo Cd Sn Sb Tl Bi
Normal 30s wash 5ppm Solution 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00
  Blank1 12.30 4.29 1.13 1.00 2.13 0.89 3.96 5.32 1.21 1.27
Uptake 15s Blank2 5.64 3.46 0.25 0.54 0.48 0.21 1.22 1.38 0.36 0.36
Read delay 8s Blank3 3.22 4.54 0.20 0.34 0.22 0.10 0.76 0.79 0.18 0.20
Data acq approx 40s Blank4 2.68 -1.70 0.13 0.20 0.15 0.08 0.59 0.62 0.14 0.12
Wash 30s Blank5 1.90 2.16 0.21 0.00 0.14 0.07 0.41 0.44 0.11 0.13
Total estimated time 1m33s Blank6 1.49 0.44 0.19 0.07 0.13 0.09 0.36 0.36 0.11 0.15
Total actual time 1m40s                      
(additional time autosampler moving etc)                      
                       
                       
                       
    B Fe Zn Se Mo Cd Sn Sb Tl Bi
Niagara 10s wash 5ppm Solution 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00 5000.00
  Blank1 8.97 1.88 1.06 0.71 3.13 0.80 5.14 9.32 1.07 1.06
Uptake 15s Blank2 5.43 7.59 0.29 0.53 0.59 0.24 1.59 2.05 0.37 0.37
Read delay 8s Blank3 3.16 6.95 0.27 0.31 0.35 0.18 0.97 1.23 0.25 0.27
Data acq approx 40s Blank4 2.21 1.26 0.22 0.12 0.22 0.13 0.71 0.91 0.16 0.17
Wash 10s Blank5 2.26 7.33 0.18 -0.09 0.13 0.07 0.49 0.54 0.11 0.13
Niagara delay 22s Blank6 1.55 4.48 0.12 0.07 0.09 0.05 0.38 0.44 0.08 0.09
Total estimated time 1m13s                      
Total actual time 1m20s                      
(additional time autosampler moving etc)                      
The graph below illustrates the stages of
analysis for a typical autosampler run on an
ICP-AES or ICP-MS spectrometer. Almost all of
the stages can be shortened by one means or
another. Some of these are dependent upon the
specific hardware configuration of the
spectrometer and autosampler. Some autosamplers
are designed to move faster than others and
should be investigated prior to purchase with
respect to speed if productivity is an important
criterion (stages 1 5). For AES spectrometers,
particularly, the configuration of the optical
and readout systems can significantly affect
speed of analysis (stage 4). Dual view (radial
and axial) spectrometers take two exposures for
each analyses, increasing the integration time.
Some chip-based spectrometers must take two
exposures to cover the wavelength range of the
method. Another aspect to investigate is the
readout overhead time which can be significant on
various makes and models. This paper will
address ways to increase productivity once the
spectrometer and autosampler have been procured
and installed.
The Helix oring-free nebulizer
fitting eliminates the orings that are a source
of dead volume. Likewise, the EzyFit
eliminates dead volume in the nebulizer sample
port.
Predictive Rinse
NORMAL (30-SEC. RINSE)
Sample Mode

• Estimate the sample uptake time.
• Lift the sipper from sample prior to the
  measurement.
• Conduct rinse and next sample loading during the
  previous sample
• measurement.
• Requires good estimates.
• May not rinse out high concentration samples.
• Not compatible with Auto QC Checking.
• Good for crude assays.

Niagara achieves 25 reduction in cycle time
(all results in ppb)
Faster Flows

• Small ID pump tubes at fast speed
• Small ID capillary tubes
• Small ID autosampler probe
• Minimize length of sample tubing

Rinse Mode
NIAGARA (10 SEC. RINSE)
Trial performed using Elan 6000 ICP-MS by Gavin
Robinson, Hill Laboratories, Hamilton, New Zealand
Intelligent Rinse

• Determine appropriate rinse based on the last
  sample.
• If all elements below set point 1 NO RINSE
• If an element exceeds set point 1 but not set
  point 2 STD RINSE
• If an element exceeds set point 2 MONITOR RINSE
  SOLN
• UNTIL UNDER SET POINT 1
• Excellent for high accuracy analyses.
• Little time saving for dirty samples.

CONCLUSIONS
The entire sample line from the autosampler
probe to the nebulizer should be minimized in
both length and internal diameter.
For greatest productivity for accurate analyses,
minimize dead volume on all sample introduction
components and combine Niagara with the Fast
Pump mode of operation.
Sample cycle for unattended ICP sample analysis