It is common to see cleaning solvent peaks in the mass spectra shortly after the ion source is cleaned. To avoid this, dry all cleaned metal parts in the GC oven before reassembling and reinstalling them. Use a temperature above the boiling point of the solvent but below the limit of the column. Make sure carrier gas is flowing through the column.
WARNING! Do not allow hydrogen to flow into an MSD that is not on and under vacuum.
Avoid contact between solvents and O-rings. Do not bake O-rings or parts that contain Teflon.