Prepare GC/MS For Column Maintenance

Hello Everyone,

I'm very new and don't have much experience in troubleshooting the GC-MS so I need your help. I'm operating on Agilent 7890B and 5977 MSD. Recently I've noticed very big baseline noise. I have changed the inlet septum and liner, which helped a little bit, but not enough. I suspect that contamination might be already in the column so I would like to trim the column and bake it out. Could you please let me know how should I prepare the GC and MSD for this process? I know that I have to cool the oven and inlet to room temperature, but what about the MSD and gas flow? Should I vent the MSD (the column is connected directly to MSD), and what about the carrier gas (He), should I close the cylinder?

If someone would be able to help, I will appreciate this a lot.

Thank you.

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  • Hi Garyb,

    I am not agree with this becuase if any one just remove the column from inlet and trimming or changing inlet consumables and during that time there is no flow in column and its connected with MS then vaccum suction of ms may deteriote column performance or may damage column.

    Without vent, there are so many technologies like quick swap etc can be used in GC where Aux flow supplied to maiantain pressure and vaccum of ms and column can be removed from quick swap fitting without vent.

  • If you have time to wait all day to pump down again that's fine. When you have a lot of rush samples you don't have that luxury. We have done it that way for 25 years with no problems.

  • Yes..Tips and tricks work based on environment and situation also.

    But there is always pros n cons..if succeed then okay otherwise what is recommended in manual, has to follow.

    I am happy that you succeed to use instrument without vent...

  • Hello, I understand you disconnect only the injector side of the column in order to trim it. Just be careful not to break the column closer to the transfer line because the sudden high flow can damage the pump and the oxygen entering can oxidize the hot parts of the MSD. It happened to me once...

    Indeed, venting the system is annoying due to the time lost in cooling/heating the hot parts, slowing down the pump, recovering vacuum, air and water entering the system and possible leaks appearing.

    I don't like to loose vacuum so I created a maintenance.M file where the hot parts of the MSD are at 100ºC in order to avoid oxidation when oxygen might get in the column (column must be cool or it will be damaged by oxygen). When I need to completely remove the column, I vent the system until the pump is at 40% speed, disconnect the column, plug the transfer line and pump down. The problems mentioned above are reduced and, especially, no leaks will appear.

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