Poor mass accuracy on a Xevo G2-XS in UNIFI - WKB21899

SYMPTOMS

• The mass accuracy is out of specification
• The analysis method has a LockSpray profile
• in the investigate tab, within the Reference Function, the lock mass is absent (possibly one out of two in a dual spray lock mass profile)
  
  Method/LockSpray profile processes with m/z 278.0113 and m/z 556.5766 in positive ion mode
  

In the reference function, m/z 556.2766 is present, but m/z 278.0113 is missing

In the review tab, components are missing or show a high mass error (if target by mass filter threshold is increased to 100 ppm in the analysis method)

ENVIRONMENT

• Xevo G2-XS
• Xevo G2-S
• UNIFI 1.9.4

CAUSE

Lock mass absent. LockSpray Profile needs optimization

FIX or WORKAROUND

1. Run the LockSpray setup for the profile in question.
2. Open the Analysis Method and, on the MS LockSpray tab, import the LockSpray profile that was just updated.
3. Do a test acquisition and verify all selected lock masses are present under method conditions
4. If required, optimize flow rate, Capillary Voltage or ColIision energy in the LockSpray profile. Then run LockspraySetup and import settings to achieve a lock mass signal of 2e4 to 3e5 per second during the acquisition.  
5. Save or update the method and acquire.

ADDITIONAL INFORMATION