In MassLynx, seeing doublet peaks for each expected mass acquired on the Synapt G2-Si - WKB4754

SYMPTOMS

• Seeing two peaks where only one is expected.
• Secondary peak is <0.2 Da away from the other.
• Height of the second peak is 50% of that of the other.
• Is seen regardless of what polarity or mode the MS is set to.
• Every peak in the spectrum is split into two smaller peaks and each peak is separated from its partner by the same number of time bins.
• The ratio of the amplitudes for each pair in a given spectrum is approximately the same.
• The mass difference (shown as “channels” in MassLynx) is either 16 or 32 (depending on sampling mode), regardless of which peak pairs are chosen across the mass range:
  

ENVIRONMENT

• SYNAPT G2-Si
• SYNAPT G2
• SYNAPT G2-S
• SYNAPT XS
• Vion IMS QTof
• Xevo G2-S
• Xevo G2-XS 
• Xevo G2
• Fast ADC PCB 700004981 (4727200DC1) and ADC Lite PCB 700008950 (4727200DC2)

CAUSE

ADC electronics require power cycle/refresh.

Possibly ADC fault.

FIX or WORKAROUND

1. Exit MassLynx or UNIFI.
2. Cycle electronics on the MS.
3. Restart software and confirm.

ADDITIONAL INFORMATION

Once present on a system, the symptoms remain for all subsequent acquisitions until the system is restarted. As it is rare for the PCB to enter the “problem” state, it is likely that the problem is cleared at the first restart.