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Prepare GC/MS For Column Maintenance

Agnes

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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  • 0

    We do not vent the MSD. We turn the inlet temp off then when it is cool we turn the flow off. Then take it out and clip it, install a new ferrule if necessary, reinsert, tighten, and turn the flow back on to make sure pressure holds ok, then turn heater back on.  Then we can bake it out or run a blank.

  • 0 in reply to garyb014

    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.

Reply
  • 0 in reply to garyb014

    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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