How do you clean a backstreamed GCMS?

[BismuthBlues]

Our GCMS was shut down improperly and the diffusion pump oil backstreamed into the chamber. I have deeply cleaned the chamber, the ion source, the EM, and all of the surfaces with isopropanol and DCM. The only thing I haven't cleaned is the quad. I keep seeing a large number of polysiloxane peaks in my tunes, some of them are bigger than the tune peaks. I currently have a blank ferrule in so I know its not coming from the column, but I just can not get rid of the peaks. Also, is it normal for the fins from the chamber to the diffusion pump to have oil on them? If not, how do you fix that also?

Any help would be really appreciated.

Edit: We have an agilent 5975 MS

[Bigbear]

You will most likely need to clean the quads as well. Contact the manufacturer for instructions.

[James_Ball]

Some oil droplets on the baffle fins above the diffusion pump is normal, and occasionally you will see a droplet just beside the opening on the bottom of the chamber. Anything more and it could be running too hot, or as you experienced due to improper venting.

Definitely check with Agilent, I can't remember which solvents the quads on the 5975 are compatible with, but I think the method they use is immersion of the analyzer minus the side board, source, and EM in the solvent, then rinse and repeat a few times.

[MSCHemist]

I lucked out and there was nothing on the source/quads/detector. I had a 73 where the rough pump regurgitated into the diff pump and the diff pump into the chamber a bit. there was a residue on the chamber walls and some crud inside the triode guage tube. I got that all clean, replaced the foreline pump with an E2M2 with a trap so that won't happen again.

[MSCHemist]

I lucked out and there was nothing on the source/quads/detector. I had a 73 where the rough pump regurgitated into the diff pump and the diff pump into the chamber a bit. there was a residue on the chamber walls and some crud inside the triode guage tube. I got that all clean, replaced the foreline pump with an E2M2 with a trap so that won't happen again. Just methanol and MeCl2 worked for me. If it is just diff pump fluid it is glycol based and should be soluble in methanol.

[James_Ball]

I lucked out and there was nothing on the source/quads/detector. I had a 73 where the rough pump regurgitated into the diff pump and the diff pump into the chamber a bit. there was a residue on the chamber walls and some crud inside the triode guage tube. I got that all clean, replaced the foreline pump with an E2M2 with a trap so that won't happen again. Just methanol and MeCl2 worked for me. If it is just diff pump fluid it is glycol based and should be soluble in methanol.

I run the E2M2s on all my 5973/5975s and the volatiles instruments have a molecular sieve trap at the entrance to the pump, which keeps moisture down in the oil and also helps prevent any oil vapor from getting back up the line.

I had a 5970 when I first started in the lab that ran volatiles and had not been serviced in over two years and had no trap. The oil came out milky white the first time I changed it, had traps on them ever since.

[laytox]

I'm worried I might be facing this problem as well, does the "MSD Bakeout" method do anything to help or will that just make things worse

[James_Ball]

I'm worried I might be facing this problem as well, does the "MSD Bakeout" method do anything to help or will that just make things worse

Only makes it worse if you have an air leak. Otherwise it will help bake off any high boiling compounds that might have accumulated on the source. It also makes it get rid of water quicker after having the analyzer open.