Wrong mass assignment in 5973A

[thohry]

Hi all,

We have a 5973 MSD in our lab. About 2 months ago, the instrument appeared to have a problem. It did not pass autotune and I could see the mass 219 and 502 was about 215 and 498, while mass 69 is OK. I have used manual tune to adjust (mass offset and mass gain) but it did not help. please help me to solve this problem.
I highly appreciate any ideas.

Regards

AT

[625]

That's a new one by me; never seen mass assignments that far off.

The only thing I can suggest is to clean the source, put on a new filament, reset ATUNE and DFTPP tune (if that is what you are using) to Default, and start from scratch with an ATUNE and a DFTPP tune.

You have plenty of PFTBA in the calibration vial, right?