Start in Pos Ion mode and use compound such as PPG’s to monitor MI scans across the range of masses that reflect the region you typically work within. Aquire run for 2 minutes then switch to Neg Ion mode and run for 1 minute. Switch back to Pos Ion and run for 3 minutes. If the system is charging the MI trace will drop over the 3 minutes. 5-10% drop is generally acceptable, but 15-20% or more will require attention.
This test should be performed for both scanning quadrupoles in both Pos and Neg mode. Depending upon the results seen, it can be determined which region of the MS Ion Optics requires cleaning. For help with this test, or interpretation of results and required action, please complete our tech support form for an Engineer to get in touch.