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Thermo Fisher Scientific

"Start With Spectrometer Optimization" when using Argon Humidifier

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Issue

After setting up the method to use "Start With Spectrometer Optimization", it is noticed that, during optimization, the nebulizer flow goes to 0.00 lpm. Sampling starts before the pressure in the humidifier has stabilized causing high RSDs and inaccurate reslope values.

Environment

iCAP running iTEVA issue 9.1 version 2.4.0.71

Resolution

That perceived malfunction would be normal when using the Argon Humidifier, certain automated features can not be used, intervention is required.

Verify use or non-use of Argon Humidifier with bypass and it's proper use during Plasma Ignition, Optimization and Auto Peak Adjust.

Argon Humidifier

The argon supply to the nebulizer is first passed through a humidifier, where the nebulizer gas is bubbled through a small water reservoir (as below). Humidified argon will permit the use of a standard nebulizer for samples with a dissolved solid content of up to approximately 5% m/v.

Daily Operation of Argon Humidifier Accessory

Follow the steps shown below to operate the Argon Humidifier accessory with your ICP instrument.

  1. Switch the two-way switch (Figure 34) to ‘ON-LINE’.
  2. Switch on the nebulizer gas flow from the ICP and set the flow in the range of 0.5 to 0.8 L/min (0.1 to 0.35MPa). Wait for 1 minute before proceeding to step 3.
    WARNING: if the nebulizer gas pressure exceeds 0.4 MPa the over pressure relief valve will operate and release gas to atmosphere. The nebulizer pressure should be maintained below this level.
  3. Switch the two-way switch to ‘BYPASS’.
  4. Ignite the plasma using the standard plasma ignition procedure with the two way switch in ‘BYPASS’.
  5. Allow the instrument to perform its Spectrometer Optimization procedures.
  6. When the Spectrometer Optimisation procedure has been completed, switch to ‘ONLINE’ and proceed with the required sample analysis.
    Note: If an AutoPeak routine is required, ensure that the switch is set to BYPASS. When the routine is completed, switch to ‘ONLINE’ as required before proceeding with sample analysis.
  7. When the required sample analysis has been completed, leave the two way switch in the ‘ON-LINE’ position before switching off the plasma.
  8. Before re-igniting the plasma, switch the two way switch to ‘BYPASS’.
  9. When required, re-light the plasma and repeat steps 4 to 6 as described above prior to commencing sample analysis.
    Note: If the plasma has been switched off for a long period it may be necessary to purge the Argon Humidifier to remove air. This is achieved by following steps 1 to 3 in this section.

As an interim work around, for pre-initial actions optimization when using the Argon Humidifier Accessory (until software is enhanced for this feature), follow these steps:

Run two Methods and sequence setups, the first for Optimize only with the check to "Start With Spectrometer Optimization" and with no initial action calibration and without sample(s), only Rinse(s) as needed for more stabilization time @ initial 39 sec plus 5 sec per "Rinse" and then the second Method without "Start With Spectrometer Optimization" and both Standards and Samples located.

Note: to insert "Rinse" must first add a sample, then after adding the needed rinse(s) can remove the sample so nothing has to be located in the racks and offset the next method sequence.

The first autosampler sequence will run optimize and rinse. Additional rinses can be added as needed to buy more settle time of the Argon Humidifier and mass flow control after the optimization.

There was a delay between sequences.

Then the second sequence previously located picked up after the first sequence tube locations, run will continue right on with initial action calibration and then the samples.