Chromatography Forum

I have an old HP 5970 MSD/ 5980 GC and recently started to have issues with tuning. Specifically 502 peak looks pretty bad even after cleaning the source (and with a different source too). While tuning I noticed that xray graph looks like crap. Abundances for 502 is noticeably lower than those for 219 and 69. I am still able to do some analysis but after a couple of days the sensitivity dramatically decreases for 219 and 69 peaks as well and eventually unable to gain sufficient signal for tuning. No apparent leak. Can it be that the multiplier needs to be replaced? EMV has routinely been around 2600-3000 in the past year and was working just fine.

Your multiplier voltage is _far_ too high. I'd say your multiplier has exceeded its useful life time and needs to be replaced

Even with the new multiplier, 502 doesn't look great. It looks like ion source ceramics need to be replaced.

Thanks letting us know