High Q Exactive MSMS mass error

[hhnguyen]

Our Q Exactive Plus suddenly acts up one day. The chromatogram looks normal. The instrument is freshly calibrated and the MS mass error looks fine. Mascot search gave very few hits. The MSMS mass error looks tremendously high, up to 400 mmu. The same run method used to give me ~5ppm MSMS mass error.

Any suggestions? Many thanks!

Hong

[Kelstrup]

Depends how much time you'd use, I would make sure that lock mass was disabled, check the right tune file is loaded, check that mass accuracy is ok with the same mass range as the fragment scan that gave a problem, and maybe try a manual HCD scan and check mass accuracy again. Calibrate everything again.

Or just contact support now.

[hhnguyen]

Yup, we're having the Service Engineer over =)