Poor QTof resolution on intact proteins or monoclonal antibodies (mAb) - WKB45630

SYMPTOMS

• Poor resolution (isotopic) on intact proteins or monoclonal antibodies (mAb)
• Poor resolution and intensity of charge state envelope
• Glycoforms are poorly resolved/defined

ENVIRONMENT

• Xevo QTof
• Xevo G2 QTof
• Xevo G2-S
• Xevo G2-XS
• Synapt HDMS
• SYNAPT G2-S 
• SYNAPT G2-Si
• Vion IMS QTof
• ACQUITY RDa
• BioAccord

CAUSE

Insufficient vacuum—particularly due to a PM or vent

FIX or WORKAROUND

Allow the instrument to pump down for longer time (up to a week or more).

ADDITIONAL INFORMATION

The size of intact proteins makes them vulnerable to interferences in the flight tube region, much more so than small molecules. This is why resolution of smaller molecules like GFP or LE are less likely to change dramatically with vacuum improvement.