- MS signal intensity decreases over time—by around 90% in one minute (ion block temperature at 120 °C)
- Switching between ion mode polarities restores signal intensity
- Problem observed when viewing peaks on the tune page
- Increasing the ion block temperature reduces the effect (the effect is more pronounced at 120 °C than at 150 °C)
- ACQUITY TQD
Probe position is incorrect (spraying directly onto the cone).
FIX or WORKAROUND
- Adjust the probe position to spray away from the cone.
The probe position that gives maximum intensity is not necessarily the same as the position that gives a stable signal. Tuning the probe so that the spray is not directed onto the cone also reduces the frequency with which the cone must be cleaned.