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.