Problem with Agilent 5975 MSD

[alexmillman]

Hi There,

I am having a problem with our Agilent GCMS system. The GC is fine and the problem is with the 5975 MSD.

The machine will perform one or two runs fine, then the MSD will only detect mostly only noise in subsequent runs. When this problem occurs, if a discernible peak in the mass spectrum is detected it will have the wrong mass. I have attached a couple of example spectra in this post.

Retuning the MSD will temporarily fix the issue. Before the issue occurs, the parameters in the tune report appear fairly normal. However, on retuning some parameters change dramatically. Notably the following:

Mass gain: -1099 to 88
Mass offset: -33 to -36
AMU Gain: 1045 to 3276

After retuning, the machine will do a few runs successfully before the problem returns. Once again retuning temporarily fixes the issue, with the report showing the parameters have returned to their previous lower values.

Any ideas whats wrong with our machine?
We have performed a thorough cleaning of both the ion source and detector assembly and the PFTBA vial is full. Could this point to an issue with the quad?

Thanks for your help!

Please find a google drive link with the report and MS images below

https://drive.google.com/drive/folders/ ... share_link

[mathieu_stability]

Hi Alex

The fact that you can restore MS performance after retuning points to a software issue.
The tune file atune.u is getting corrupted.
Or the electronics : smartcard/mainboard combination are unable to keep the correct amu gain and offset values.

Where are you located in UK ?
If I am in your area, I would be happy to pop in and assist.

Matt

[mburleson]

I agree with the post stating it could be corruption of the cards on the analyzer. We had similar issues for a bit with losing the tune and by resaving/rewriting the atune file, it was resolved. I'd keep an eye on the higher mass tune peak - that was how we were able to determine Agilent would need to replace our analyzer - it was dipping and staying really low in abundance and then eventually read 0.