Area values vary (poor reproducibility) with ACQUITY QDa Mass Detector/ACQUITY UPLC H-Class - WKB241564

SYMPTOMS

• Area values vary (poor reproducibility)

ENVIRONMENT

• ACQUITY QDa Mass Detector
• ACQUITY UPLC H-Class

CAUSE

Variation in injection volume, QDa detector issues, and/or analysis conditions issues

FIX or WORKAROUND

1. Check whether the analysis conditions were successfully used in the past.
   If a PDA or other detector is also connected, check the reproducibility there.
2. Check for variations in injection volume.
   If measurements were performed successfully with good reproducibility in the past, run three diagnostic tests related to SM-FTN (needle seal characterization, needle seal readiness test, sample syringe leak test).
   If all three pass, check the reproducibility in that state.
3. QDa detector maintenance.
   If measurements were performed successfully with good reproducibility in the past, and if maintenance has not been performed on the QDa detector for a while, it may be possible to improve reproducibility with maintenance.
   ・Clean the sample cone.
   ・Replace the aperture disk.
   For details, see the ACQUITY QDa Detector Overview and Maintenance Guide.
   (User registration is required only for the first download. After logging in to our website, click the above URL.)
4. Improving sensitivity.
   If there is no history of successful measurements with good reproducibility, and if the reproducibility is poor compared with PDA detectors,
   MS detectors are inherently less reproducible than UV and other detectors.
   If variations are particularly noticeable in the low concentration range, it may be possible to improve reproducibility by improving the original sensitivity.
   For consideration of SIR conditions for QDa detectors, refer to the following KCS article:
   How to optimize the ACQUITY QDa Mass Detector SIR conditions? - WKB82044
   Also, if it is possible to make changes, it is possible to increase the area value itself by increasing the injection volume in order to improve reproducibility.

ADDITIONAL INFORMATION