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Thermo Fisher Scientific

FID Analog Filter

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A customer operating several Focus GCs with FID using Chromquest software has experienced baseline drift down to around 0.0 mV on two systems. This issue, common when using analog filters, can be resolved by setting the ignition threshold to 0.0 mV. This solution applies to systems using Chromquest, Chromeleon, and Xcalibur. To confirm the GC is working, remove the analog filter and check if the signal is around 2-7 mV.

Issue

  • A customer has several Focus GC with FID operating with Chromquest software.  
  • The customer operates one Focus GC in the mode of analog filter range 1 and one Focus GC at an analog filter range of 100 as the samples have high concentrations.
  • The baseline on two of the systems has drifted down and is now around 0.0 millivolts (mV).  
  • The customer is currently running with a ignition threshold of 0.0 mV and the FID remains ignited.  
  • I discussed this issue with another Technical Support Representative and they indicated this is a common issue when using Analog filters and to overcome the issue the ignition threshold is set to 0.0 mV . 
  • The customer is using Chromquest as the software, and this will also be an issue with Chromeleon and Xcalibur.

Environment

  • Trace Ultra
  • Trace 1300
  • Trace 1310
  • ChromQuest
  • Chromeleon
  • Xcalibur

Resolution

  • The only solution is to run with threshold set to 0.0. 
  • User can confirm that GC is working by removing the analog filter and confirming the signal is around 2-7 mV.