Large artifact peak, no real signal on QToF instrument - WKB51479

SYMPTOMS

• Large artifact Peak at 286 Da in Negative Resolution mode
• Peak is visible in Operate and Source Standby
• All other modes have normal signal
• Low-mass peaks are still visible when zoomed in and have the proper resolution and isotopic pattern

ENVIRONMENT

• SYNAPT G2-Si
• Xevo G2-XS QTof

CAUSE

Veff value in Acquisition Settings was reset to 1000.

FIX or WORKAROUND

1. Copy the Veff value from Negative Sensitivity mode.
2. Fine-tune the Veff value to give the correct mass for leucine enkephalin.

ADDITIONAL INFORMATION

Correct settings:

The m/z of the artifact peak is dependent on the Veff value setting. On the Xevo G2-XS, Veff was set to 1700 and the artifact was 374.5. Set the Veff to whatever settings work in the working mode for the same polarity.