10 Replies Latest reply on Feb 9, 2018 7:03 AM by james_jenkins

Noise peaks on Agilent 7820A using TCD

plaraia Jan 9, 2018 6:57 AM

Unit is generating random baseline noise that is not caused by line voltage ( has been checked). We are running concentrated halocarbons on a TCD detector . Unit is only 2 years old. My thought is the TCD detector but can anything be done to quiet it down? It will eventually go away, not sure why.

thank you

Re: Noise peaks on Agilent 7820A using TCD

apcharles Jan 9, 2018 7:02 AM (in response to plaraia)

Hello Plaraia,

Could you tell me what your data rate for the TCD is on your method? You should be able to find in the [edit method] in your software under the detector tab.

thank you
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- Re: Noise peaks on Agilent 7820A using TCD
  
  plaraia Jan 9, 2018 7:24 AM (in response to apcharles)
  
  5 Hz/ 0.04 min
  
  Thanks
  
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  - Re: Noise peaks on Agilent 7820A using TCD
    
    apcharles Jan 9, 2018 8:05 AM (in response to plaraia)
    
    Plaraia,
    
    The data rate setting is fine. That is the recommended setting for the TCD.
    A noisy baseline could usually indicate a leak, contamination, or electrical problem depending on how the baseline looks.
    You mentioned that the noise comes and goes, which could indicate a possible contamination. Electrical issues are a bit more consistent.
    Have you made any recent changes to the instrument?
    
    Possible troubleshooting options:
    -check the system for leaks (ie: column fitting)
    -perform any maintenance on the inlet and column, if you haven't done so already (ie: change the septum, liner, oring, clip the end of the column
    -check for any loose connections on the detector
    -bakeout any contaminants in the column, inlet , and detector
    -verify the purity of the gas being used. If you have a filter or trap on the line, check the age. It is usually recommended that they are changed every 6 months
    
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    - Re: Noise peaks on Agilent 7820A using TCD
      
      plaraia Jan 9, 2018 8:12 AM (in response to apcharles)
      
      Thanks, We eventually do all of those things but can never pinpoint the true root cause. I am going to try one at a time this time to see if I can get there by process of elimination.
      Thanks
      
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Re: Noise peaks on Agilent 7820A using TCD

james_jenkins Jan 9, 2018 7:08 AM (in response to plaraia)

Tags have been updated for better visibility.
James
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Re: Noise peaks on Agilent 7820A using TCD

james_jenkins Feb 9, 2018 3:00 AM (in response to plaraia)

Hi plaraia,
I marked this assumed answered due to the age, if thats not the case, please feel free to post more questions. If you have solved it using apcharles suggestions you can mark correct and this will help others. We look forward to interacting with you in the community again.
Regards
James
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- Re: Noise peaks on Agilent 7820A using TCD
  
  plaraia Feb 9, 2018 6:18 AM (in response to james_jenkins)
  
  James, I never did find out what caused noise to come but it eventually went away. I did raise injected temp overnight then lowered it back. It didn’t help immediately. Older analysts say this is a phenomenon that happens with TCD and our materials ( halocarbons) It does not make sense to me? Can a TCD “self clean” itself? Material we inject is typically over 90% pure.
  
  Paul
  
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  - Re: Noise peaks on Agilent 7820A using TCD
    
    james_jenkins Feb 9, 2018 6:52 AM (in response to plaraia)
    
    Hi plaraia,
    The TCD is a heated filament and if there is a coating of the filament I guess it could come off with time. It sounds like the resources you have in your lab may have experience with this. When it comes to sample being pure, sample that reacts with a detector no matter how pure does have the ability to add deposit or coating or react with the filament. You can also get coating or deposit from stationary phase from the column etc .
    Regards
    James
    
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    - Re: Noise peaks on Agilent 7820A using TCD
      
      plaraia Feb 9, 2018 7:00 AM (in response to james_jenkins)
      
      There is no other way to clean a TCD that you know of other than raising up the detector temp? It took about 4 days for system to finally calm down.
      
      Thanks
      
      Paul
      
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      - Re: Noise peaks on Agilent 7820A using TCD
        
        james_jenkins Feb 9, 2018 7:03 AM (in response to plaraia)
        
        Hi Paul,
        None that I am aware of that is supported from Agilent.
        James
        
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