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Decrease in MRM sensitivity with Xevo TQD - WKB7496

Article number: 7496

SYMPTOMS

  • Sudden drop in sensitivity for MRM experiments

ENVIRONMENT

  • Xevo TQD
  • Xevo TQD IVD

CAUSE

  • Dirty ion optics
  • Issue with collision-gas pressure or supply

FIX or WORKAROUND

  1. Determine if the sample cone and cone gas nozzle are clean.
  2. Check the collision-gas pressure setting on the output of the gas regulator (it should be set to 7.0 +/- 2 psi).
  3. 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).
  4. After corrective action, perform a sensitivity check and verify that sensitivity is back. 

ADDITIONAL INFORMATION

  • 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

 

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