ACQUITY TQD signal intensity decreases over time - WKB4797

SYMPTOMS

• 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)

ENVIRONMENT

• ACQUITY TQD

CAUSE

Probe position is incorrect (spraying directly onto the cone).

FIX or WORKAROUND

1. Adjust the probe position to spray away from the cone.

ADDITIONAL INFORMATION

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.