Poor Sensitivity Or Sudden Loss In Sensitivity; Poor High Mass Response; Poor Sensitivity In Ci Mode - Thermo Scientific ISQ 7000 Hardware Manual

Poor sensitivity or sudden loss in sensitivity.

Possible Remedies
Tune the system.
Refill the calibration gas reservoir.
Perform a daily tune check to determine if you are getting the correct response to the calibration gas. Verify the leak check is below 7%.
If the calibration gas sensitivity is low, switch to the second filament and tune the ISQ 7000 instrument to determine if the calibration gas
sensitivity is recovered. If so, continue to run with the second filament.
Make sure the ion volume is properly positioned. See
source, remove the ion source, verify that it is assembled correctly, and reinsert it into the ISQ 7000 instrument.
Make sure the GC column does not extend into the ion source. Use the column measuring tool to ensure the column is the correct length.
Make sure the GC column did not break inside the ion source. If necessary, remove the pieces from the ion source.
Clean or replace the GC injection port liner to remove possible contamination, trim the injector end of the column, or replace the septum.
Make sure the source magnets are positioned so that their south poles are facing up. Reposition them, if necessary.
Clean the ion source and lenses. See
Make sure the right type of ion volume is installed. EI and CI require different ion volumes and cannot be used interchangeably.
Check the electron multiplier gain and make sure it is not too low. Retune the detector gain. Replace the electron multiplier, if necessary.
See Replacing the Electron Multiplier

Poor high mass response.

Possible Remedies
Run a resolution tune to make sure the resolution is set correctly.
Refill the calibration gas reservoir.
Clean the ion volume and lenses. See
Reduce the ion source temperature to reduce the amount of thermal decomposition and fragmentation of your analyte.
Check the system for air leaks and address them. See

Poor sensitivity in CI mode.

Possible Remedies
Make sure a CI ion volume is installed.
Make sure the electron entrance hole on the CI ion volume is clean. Use a dental pick or old syringe needle to clear the hole. See
Durable Components if you need help locating the electron entrance hole.
Thermo Scientific
Ion Source Cartridge
Cleaning the Ion Source Cartridge
for details.
Cleaning the Ion Source Cartridge
Investigating Vacuum Issues
for details. If you recently performed maintenance on your ion
for details.
for details.
for details.
2
Troubleshooting
Investigating Sensitivity Issues
Cleaning
ISQ 7000 Hardware Manual 139