Possible leak after maintenance was performed

After having an air water check the Nitrogen level is not receding below 5% and now water and O2% is also increasing. What can be the probable cause.  I check for leaks at all the tubing connections, everything seems fine

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  • I split this new subject out from your previous one.

    If there is water in the background, there will always be some apparent air - 28/32.  When the water goes down the air will also. 

    What's the last thing that was done?  A new tank of carrier gas?   Did you clean the source or something else?

  • Yes the source was cleaned and the gas tank was replaced as well. Also I recalibrated the instrument  and updated the RT for my analytes but for my  samples none of the analyte is picking up the correct peak and RTs are off

  • What is the current status of the instrument? Please upload a copy of the current autotune report.

  • From MassHunter Acquisition Help:

    A Quick Tune report does not necessarily tell the entire story as it is not a complete tune.  However, I think this tells enough to address your concern about a possible leak.  The report says that Nitrogen is ~9.9% of the 69 abundance and Oxygen is only ~0.7%.  In air, the Nitrogen to Oxygen ratio is about 4:1.  So if it is an air leak, the Oxygen would be closer to 2.5% ...or conversely, the Nitrogen would be only about 2.8%.

    Since the Nitrogen is high, that is either Nitrogen in the carrier gas. an air leak before an oxygen trap, or residual Nitrogen coming out of a newly-replaced gas trap.  Most gas filters are packed with Nitrogen and not Helium and residual Nitrogen can take time to purge out of the pores in the trap material.

    To read about how to purge the regulator and traps see: (+) How to Change Your Helium GCMS Carrier Gas Tank - Two ways - Files - GC/MS - Agilent Community

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  • From MassHunter Acquisition Help:

    A Quick Tune report does not necessarily tell the entire story as it is not a complete tune.  However, I think this tells enough to address your concern about a possible leak.  The report says that Nitrogen is ~9.9% of the 69 abundance and Oxygen is only ~0.7%.  In air, the Nitrogen to Oxygen ratio is about 4:1.  So if it is an air leak, the Oxygen would be closer to 2.5% ...or conversely, the Nitrogen would be only about 2.8%.

    Since the Nitrogen is high, that is either Nitrogen in the carrier gas. an air leak before an oxygen trap, or residual Nitrogen coming out of a newly-replaced gas trap.  Most gas filters are packed with Nitrogen and not Helium and residual Nitrogen can take time to purge out of the pores in the trap material.

    To read about how to purge the regulator and traps see: (+) How to Change Your Helium GCMS Carrier Gas Tank - Two ways - Files - GC/MS - Agilent Community

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