- Sudden drop in sensitivity for MRM experiments
- Xevo TQD
- Xevo TQD IVD
- Dirty ion optics
- Issue with collision-gas pressure or supply
FIX or WORKAROUND
- Determine if the sample cone and cone gas nozzle are clean.
- Check the collision-gas pressure setting on the output of the gas regulator (it should be set to 7.0 +/- 2 psi).
- With collision gas on, check the collision-gas pressure readback on the Tune page. It should be 3.5–4.0e-3 mbar. If the readback is not within the specified range, adjust the regulating screw on the argon gas flow controller inside the instrument (see the Additional Information section below).
- After corrective action, perform a sensitivity check and verify that sensitivity is back.
- Occasionally, the same symptoms will result from a malfunctioning RF generator or an issue with the ESI probe.
- For more information see the following KCS article:
- KCS 2364: Loss of Sensitivity on TQ Detector