Ran the positive mass calibration using thermos's Peirce positive calibrant, but it failed due to not finding the MRFA peak at m/z 524.265.
I initially thought I could be the calibrants as they were old, so we bought new calibrant. No change.
I then thought I could be a dirt ion source etc. So, I cleaned the ion source housing, sweep cone, and ion transfer tube. Then flushed the system with 98% H2O + 0.1% formic acid (FA) and 2% MeOH + 0.1% FA for about half a day. No change.
Then flushed the system with 50:50, H2O + 0.1% FA:MeOH + 0.1% FA, for a whole day almost. No change.
My colleague suggested a system reset, which was performed....still no change.
-My worry is there may be some contamination deep inside the MS, that is breaking down MRFA as it is traveling through the system.
Does anyone have any ideas on what we could do next?
An ex-Thermo FSE taught me this, so it may be worth a shot. While infusing a standard and observing its peaks, enabling and disabling either the skimmer offset or source collision may show a shift in signal. If it does, all optics before the quad need to be cleaned.
I'd clean everything again up to and including the skimmer. Do you have alumina powder or Bar Keeper's Friend? Both are great for cleaning and polishing the optics. After I clean/polish them with either of those, I rinse them in ultra-pure water and then sonicate them in a dilute acid. I like to use dilute nitric for everything BUT the tube lens. It will discolor and ruin in nitric, so for it I use a 50:25:25 water:MeOH:IPA solution.