Chromatography Forum

Hi all, I just started working on an older GC/MSD (6890/5973) that required an ion source cleaning. I cleaned the source, but then realized an air leak was present in the system. For about 2 weeks (while I found and fixed the leak) the cleaned source was under the air leak conditions.

The leak is now fixed. Would you (or should I) re-clean the source after the air leak has been fixed? I have heard that O2 from the air can re-oxidize the system. The instrument is being used to run for VOCs.

Thanks!

You may have no issues if running VOCs. I would let your BFB determination be the guiding factor. If it works and you like the chromatography, I'd run with it. Make note of the leak, maybe even abandon that filament for the other if you suspect it's shot. Failing BFB criteria could be a sign that filament is done.

It depends on how big the leak was and how long it leaked. I have had a 5971 in the past that had a leak that would show as about 10% air in the air/water check but could run it for 6-8 months at that level without any problems. If it tunes and gives good sensitivity then it should be ok. Your source internals may have a gold or blue color the next time you clean it, but it doesn't affect the sensitivity as much as some high boiling organics will.