Excessive Noise Or Low Signal-To-Noise Ratio - Agilent Technologies 7250 Troubleshooting And Maintenance Manual

3 CI Troubleshooting
The CI ion source is dirty.
Clean the ion source. See the Agilent 7250 Accurate-Mass Quadrupole
Time-of-Flight GC/MS System Operating Manual.
The calibration valve was not purged after the vial was refilled.
Purge the calibration valve as described in
page 90. Then clean the ion source.
The calibrant vial was overfilled. Excess PFDTD can quench the chemical
ionization reactions.
Check the level of the PFDTD in the calibration vial. It should be below the end of
the inside tube in the vial.
Poor quality methane (purity below 99.99%)
Replace the methane with high-purity methane. If necessary, clean and purge the
reagent gas lines and clean the ion source.

Excessive noise or low signal-to-noise ratio

The GC inlet needs maintenance.
Refer to the GC manual.
The CI ion source is dirty.
Clean the ion source. See the Agilent 7250 Accurate-Mass Quadrupole
Time-of-Flight GC/MS System Operating Manual for more information.
Poor vacuum
Check the pressure on the high vacuum gauge controller.
Air leak
Run an air and water check. See the software online help for additional
information.
Saturated methane/isobutane gas purifier
Replace the gas purifier. See
Purifier"
62
on page 88.
7250 Accurate-Mass Q-TOF Troubleshooting and Maintenance Manual
"To Refill the CI Calibration Vial"
"To Replace the Chemical Ionization Gas
on