Chromatography Forum

We lost power to our entire GC 6890-MS 5973 system for about 15 minutes or so.
When power returned it pumped down almost instantly. After auto tuning I did the air and water check and system evaluation.
The system evaluation was ok except "Mass 502 Precursor (<= 12%)" and the value recorded was 16.00
The message "Contact your Agilent Technologies Customer Engineer" appeared underneath that line. I contacted them by the way and they didn't know the cause and said it probably wouldn't affect our analysis anyway. There was also the message "One or more specifications was out of range. Please correct before continuing."
After changing to a method with a higher flow rate and less vacuum (which is more consistent with previous autotunes) I did the tune again and the system evaluation. The Mass 502 value now changed to 13.82, so it appears that it's dropping. Any advice on what I should do (or not do)? Any ideas how the power outage is related to the sudden high abundance of 502?

Also on a tune I did exactly one month ago I noticed the 502 peak start to develop a small hump on the left side at roughly 2.5x the height of the small peak to the right of the main peak. After the power outage after an autotune and spectra tune the hump got a little smoother. After an autotune this morning it got a lot 'sharper' so that it has formed a tiny small peak with no tail connected to the large peak. How can I make it go smooth again so there is no split peak?

One cause of a precurser is a high repellor setting. You may try lowering this to see if the precurser merges back into the main 502.

You could also have some minor contamination on the quads themselves which will cause minor problems with mass peak shapes, especially at higher masses.

If it begins to develop at lower masses and you have drifting peak widths then you have to worry about the side board going bad.

Also, have you "DIPed the quads" (as in adjusted the big screws on the side board)? This is how you fine tune the quad drivers for best resolution.

I've also started to get this. Showed up today after we briefly lost power last night. All of our analytes are below 500, most below 300, so not too worried. Working on it today, will post back then....